Welfare of horses at slaughter

Abstract

The objective of this Scientific Opinion is to assess the hazards and welfare consequences associated with the slaughter of horses for human consumption. The entire slaughter procedure, from arrival at the slaughterhouse until death, is divided into three phases: Phase 1 – pre‐stunning, Phase 2 – stunning and Phase 3 – bleeding. Phase 1 includes the following processes (in chronological order): (a) arrival, (b) unloading of the animals from the vehicle, (c) lairage, (d) handling and moving to the stunning area and (e) restraint before application of the stunning method. Phase 2 encompasses the stunning methods, while Phase 3 involves the bleeding process (i.e. exsanguination following stunning). Stunning methods for horses include penetrative captive bolt and firearms. Welfare consequences that horses may experience (such as handling stress, restriction of movement and injuries) and potential hazards were identified for all the phases along with preventive and corrective measures. For arrival and unloading during phase 1, this Opinion refers to a previous EFSA assessment on the transport of Equidae. Animal‐based measures (ABMs) to assess all identified welfare consequences are proposed. A flowchart of ABMs to assess the state of consciousness is provided to allow monitoring during the stunning and bleeding phase at three key stages ((1) between the end of stunning and shackling, (2) during neck cutting or sticking, (3) during bleeding). Additionally, specific practices deemed unacceptable on welfare grounds are listed.

SUMMARY

In 2009, the European Union (EU) adopted Council Regulation (EC) 1099/2009 ‘on the protection of animals at the time of killing’, which was prepared based on two Scientific Opinions adopted by the European Food Safety Authority (EFSA) issued in 2004 and 2006.

Against this background, the European Commission (EC) requested EFSA to write a Scientific Opinion providing an independent view on the slaughter of horses. Specifically, EFSA was asked to: (i) identify the animal welfare hazards and their possible origins in terms of facilities/equipment and staff; (ii) define qualitative or measurable criteria to assess performance on animal welfare (animal‐based measures (ABMs)); (iii) provide preventive and corrective measures (structural or managerial) to address the identified hazards; and (iv) point out specific hazards related to species or types of animals. In addition, the mandate requested a list of methods or practices considered unacceptable on welfare grounds.

This Scientific Opinion addresses the killing of horses for human consumption in a slaughterhouse or during on‐farm slaughter, with the aim of updating previous EFSA outputs by reviewing the most recent scientific publications.

The approach used to address the mandate follows a protocol previously developed by EFSA: in summary, for the identification of most elements requested in the mandate (e.g. stunning methods, hazards, ABMs) the protocol is based on expert collective judgement, for the identification of welfare consequences (WCs) occurring to the animals the protocol is based on an exercise of expert knowledge elicitation (EKE), whereas for the description of the elements requested in the mandate, extensive literature searches were used.

Firstly, EFSA experts identified the processes related to the slaughter of horses that should be included in the assessment. The whole slaughter is divided into Phase 1 (pre‐stunning), covering the following processes (in chronological order): (a) arrival, (b) unloading of the animals from the vehicle, (c) lairage, (d) handling and moving to the stunning area and (e) restraint; Phase 2 (stunning) including the relevant stunning methods; and Phase 3 (bleeding) involving exsanguination following stunning.

Secondly, the experts identified the highly relevant WCs that horses may experience during each process. ABMs for assessing these WCs were also identified. Through Expert Knowledge Elicitation, the highly relevant WCs were determined for the following processes of Phase 1: (i) lairage, (ii) handling and moving and (iii) restraint. For arrival and unloading, this Opinion refers to a previous EFSA Opinion on the transport of Equidae, and the highly relevant WCs were drawn from that assessment. In Phase 2 (stunning) and Phase 3 (bleeding), animals might experience highly relevant WCs (e.g. injuries) and underlying negative affective states, i.e. pain and fear, only if they are conscious (e.g. due to mis‐stunning or recovery of consciousness). For this reason, the focus for Phase 2 and Phase 3 is to prevent the presence of consciousness following stunning.

Thirdly, the experts produced a list of possible welfare hazards present during each process and identified corrective measures that can prevent the related WCs. Additionally (or when corrective measures were not considered feasible), measures to mitigate the WCs were proposed.

Uncertainty assessment was performed on key conclusions that could be considered for risk management decisions (e.g. those on the application of the stunning methods). These assessments are presented in a separate chapter, with the certainty level indicated in brackets within relevant conclusions.

Related to Phase 1, upon arrival at the slaughterhouse horses may experience gastro‐enteric disorders, heat stress, injuries, prolonged hunger, prolonged thirst, respiratory disorders, resting problems, restriction of movement and sensory overstimulation. To prevent heat stress, the temperature inside the vehicles (i.e. until unloading) should not exceed the upper critical temperature of 25°C (dry‐bulb temperature). If horses show signs of heat stress, mitigative measures should be applied such as parking the vehicle in the shade, enhancing ventilation or offering water if drinkers are available. If horses are experiencing restriction of movement due to lack of horizontal space (i.e. for horses transported in group, at stocking density above 200 kg/m²; for horses transported individually with less than 40 cm to the side of the horse at the largest point of the body or less than 40 cm in addition to the body length of the horse) or vertical space (i.e. less than 75 cm from the withers to the deck), they should be unloaded and either be slaughtered immediately or be provided with sufficient space in lairage.

During unloading, horses may experience handling stress, heat stress, injuries, restriction of movement and sensory overstimulation. The unloading ramp should be adequate (i.e. slope < 20° and fitted with a system that facilitates foothold, such as foot battens). The ramp should have side barriers, be stable and not emit loud noises when used. Covering the ramp with straw, sand or sawdust can prevent slipping as well as reduce noise and thereby decrease the risk of restriction of movement, injuries and sensory overstimulation. Staff should be skilled in handling horses and able to adapt to horse species and individual specific needs in order to minimise handling stress.

In lairage, horses may experience group stress, heat stress, injuries, prolonged hunger, prolonged thirst, resting problems, restriction of movement, sensory overstimulation and separation stress. To avoid group stress, mixing of unfamiliar groups of horses should be avoided. Instead, it is recommended to keep familiar groups together or to house horses in individual pens. Stallions are prone to fight and should be penned individually. To avoid separation stress, mares and foals should be kept together in the same pen. Ventilation should be provided in lairage to maintain the temperature below 25°C. Drinking water should be provided. Feed should also be provided if the horses are expected to stay in lairage for a long time (i.e. if the expected total time would exceed 12 h from the last meal). For horses lairaged in collective pens, the adequate space to prevent resting problems and restriction of movement corresponds to a maximum stocking density of 110 kg/m². For horses lairaged in individual stalls, the adequate free space for movement corresponds to 40 cm in addition to the horse's maximum width and 40 cm in addition to the body length. A minimum vertical space of 2.7 m (floor‐to‐ceiling height) should be provided. Lastly, suitable bedding should be provided for stays of more than 12 h to limit resting problems.

During handling and moving of horses to the stunning area, the WCs include handling stress, injuries, restriction of movement, sensory overstimulation and separation stress. In order to prevent restriction of movement, passageways should have a width of about 80 cm for an average horse and the width needs to be adjusted for exceptionally large or small animals. Painful or fearful stimuli (such as electric goads, hitting with a stick or shouting) should not be used. To prevent separation stress, handled animals should be moved one by one with a halter and rope or in groups and always remain in sight of at least one other animal. Semi‐feral and unhandled horses should be moved in small groups or pairs.

During the restraint process, horses experience restriction of movement and may additionally experience injuries and sensory overstimulation. The animals should only be restrained when the operator is ready to perform stunning. The size of the stun box should be adjusted to fit the horse, so that the animal cannot move back or forward or turn around, thereby minimising the risk of injuries. In addition, the duration of restraint should be kept at a minimum. Floors in the stun box should be kept clean and dry to avoid slipping.

Related to Phase 2 (stunning), penetrative captive bolt is the most commonly used stunning method for horses. Firearms with free bullets are also used, as a one‐step stunning and killing method. Ineffective stunning and recovery of consciousness cause pain and fear. ABMs for assessing consciousness are used to indirectly assess pain and fear, and a flowchart of ABMs to assess the state of consciousness is suggested in this Scientific Opinion to allow monitoring during the stunning and bleeding phase (see Figure 5) at three key stages ((1) between the end of stunning and shackling, (2) during neck cutting or sticking, (3) during bleeding).

FIGURE 5.

Flowchart of ABMs to monitor the state of consciousness to be used at three key stages. If any sign of consciousness is observed at any stage, an intervention should be applied (i.e. re‐stunning or backup method).

The recommended parameters for captive bolt leading to effective stunning are: minimum bolt diameter of 9 mm, minimum bolt length of 8 cm and speed of at least 55 m/s. The appropriate shooting position for captive bolts and for firearms is 1 cm above the intersection of a diagonal line extending from the centre of an eye to the centre of the opposite ear. The bolt should be directed towards the brain stem for maximum effectiveness.

Related to Phase 3 (bleeding), the lack of skilled operators and the use of blunt or short knives, leading to incomplete sectioning of the brachiocephalic trunk or of the carotid arteries, may result in recovery of consciousness during bleeding and delayed onset of death. The bleeding of ineffectively stunned animals and of those recovering consciousness following stunning leads to severe pain and fear. The stun‐to‐stick interval should be as short as possible and always below 60 s. Death should be confirmed before carcass processing begins.

Lastly, some practices considered unacceptable on welfare grounds (e.g. severing the spinal cord, use of electric goads to move the animals etc) are listed. These practices must not be used.

1. INTRODUCTION

1.1. Background and Terms of Reference as provided by the requestor

1.1.1. Background

The Union adopted in 2009 Council Regulation (EC) No 1099/2009 ¹ on the protection of animals at the time of killing. This piece of legislation was prepared on the basis of two EFSA opinions respectively adopted in 2004 ² and 2006. ³ The EFSA provided additional opinions related to this subject in 2012, ⁴ 2013, ^{5 , 6 , 7 , 8 , 9 , 10} 2014, ^{11 , 12} 2015 ¹³ and 2017. ^{14 , 15}

In parallel, since 2005, the World Organisation for Animal Health (WOAH – formerly called OIE) has developed in its Terrestrial Animal Health Code two chapters covering a similar scope:

− Slaughter of animals (Chapter 7.5).

− Killing of animals for disease control purposes (Chapter 7.6).

The chapter “slaughter of animals” covers the following species: cattle, buffalo, bison, sheep, goats, camelids, deer, horses, pigs, ratites, rabbits and poultry (domestic birds as defined by the WOAH).

The WOAH has created an ad hoc working group with the view to revise the two chapters.

Against this background, the Commission would like to request the EFSA to review the scientific publications provided and possibly other sources to provide a sound scientific basis for future discussions at the international level on the welfare of animals in the context of slaughter (i.e., killing animals for human consumption) or other types of killing (i.e., killing for other purposes than slaughter).

1.1.2. Terms of Reference

The Commission therefore considers it opportune to request EFSA to give an independent view on the slaughter of animals (killing for human consumption) concerning two categories of animals:

• − free moving animals (cattle, buffalo, bison, sheep, goats, horses, pigs).
• − animals in crates or containers (i.e. rabbits and domestic birds).

The request covers the following processes and issues:

• − arrival of the animals,
• − unloading,
• − lairage,
• − handling and moving of the animals (free‐moving animals only).
• − restraint,
• − stunning,
• − bleeding,
• − slaughter of pregnant animals (free‐moving animals only).
• − emergency killing (reasons and conditions under which animals have to be killed outside the normal slaughter line),
• − unacceptable methods, procedures or practices on welfare grounds.

For each process or issue in each category (i.e. free moving/in crates or containers), EFSA will:

• − ToR‐1: Identify the animal welfare hazards and their possible origins (facilities/equipment, staff),
• − ToR‐2: Define qualitative or measurable criteria to assess performance on animal welfare (animal‐based measures (ABMs)),
• − ToR‐3: Provide preventive and corrective measures to address the hazards identified (through structural or managerial measures),
• − ToR‐4: Point out specific hazards related to species or types of animals (e.g., young, with horns).

1.2. Interpretation of the Terms of Reference

This Scientific opinion concerns the slaughter of horses for human consumption. A separate opinion deals with the welfare of horses when killed on‐farm for purposes other than slaughter.

In the present opinion the term ‘horses’ is used to indicate horses of all heights, therefore including ponies.

This opinion will use definitions related to the slaughter of horses provided by the Council Regulation (EC) 1099/2009 of 24 September 2009 on the protection of animals at the time of killing, which entered into force in January 2013. In this opinion, ‘slaughter’ refers to any intentionally applied procedure that causes the death of an animal for human consumption.

The phases considered in this Opinion include the period from arrival until the animal is dead, and are Phase 1 – pre‐stunning, Phase 2 – stunning and Phase 3 – bleeding. Phase 1 includes the following processes (in chronological order): (a) arrival, (b) unloading animals from the vehicle, (c) lairage, (d) handling and moving to the stunning area and (e) restraint. Phase 2 describes the stunning methods while Phase 3 covers bleeding i.e. the exsanguination following stunning.

Slaughter may occur in a slaughterhouse but also on a farm. In this opinion, the focus is on slaughter in slaughterhouses. For on‐farm slaughter, horses are already in situ, therefore, related to Phase 1, the processes (a) arrival, (b) unloading animals from the vehicle and (c) lairage are not applicable. The processes (d) handling and moving to the stunning area and (e) restraint, are described in the separate opinion dealing with on‐farm killing, including specificity to the on‐farm context (e.g. handling and moving from the home pen or from pasture directly to the killing point, restraint performed with temporary built boxes etc). Related to Phase 2 and 3, the present opinion should be referred to, because the methods for stunning and bleeding during on‐farm slaughter are the same as those used in the slaughterhouse.

Per each phase and process, the mandate requests the assessment of hazards, related ABMs, hazards' origin and preventive/corrective actions.

The mandate does not request the identification of relevant WC during slaughter. However, in line with the EFSA guidance on risk assessment in animal welfare (EFSA AHAW Panel, 2012a), the identification of WCs that horses can experience is a necessary step for the subsequent identification of hazards as requested by the mandate. Therefore, in this opinion, WCs were identified per phase of the slaughter. The methodology developed for the identification of WCs follows the EFSA guidance on risk assessment in animal welfare in the context of the F2F strategy revision (EFSA AHAW Panel, 2022a).

During Phase 1 (pre‐stunning), the assessment identified highly relevant welfare consequences that could result in negative affective states, particularly pain and/or fear. Phase 2 (stunning) and Phase 3 (bleeding) involve the application of stunning methods intended to render the animal unconscious and to ensure the animal is dead. The analysis of welfare consequences in Phase 2 and Phase 3 is based on the assumption that the animal is rendered unconscious at the start of Phase 2, as required by Council Regulation (EC) 1099/2009. Consequently, negative affective states such as pain and fear are not expected to occur unless the animal is mis‐stunned or regains consciousness during these phases. If consciousness is present in Phase 2 or Phase 3, the animal may experience negative affective states stemming from the welfare consequences identified in Phase 1 (e.g. pain from restriction of movement) as well as from WCs resulting from the stunning or bleeding method (e.g. pain due to neck cutting).

For that reason, the negative affective states of pain and fear are directly linked to the animal's conscious state. Preventing consciousness after stunning is therefore critical to avoid these states during Phase 2 and Phase 3. As structured in this scientific opinion, the identified welfare consequences in Phase 1 serve as the foundation for understanding the potential for pain and fear in later phases, should stunning fail or consciousness be regained.

Pain is defined as an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage (Raja et al., 2020). Fear is defined as an unpleasant emotional affective state, induced by the perception of a danger or a potential danger that threatens the integrity of the animal (Boissy, 1995). Consciousness is defined as the capacity to receive, process and respond to information from internal and external environments, and therefore the ability to feel emotions and be sensible to external stimuli (Le Neindre et al., 2017).

According to Council Regulation (EC) 1099/2009, slaughter should spare animals from unnecessary pain, distress and suffering. However, EFSA experts consider that distress and suffering might include pain and fear (as sensorial and emotional components), and therefore the focus of this opinion is on minimising pain and fear throughout slaughter.

The slaughter of horses typically occurs in dedicated facilities where animals are transported, resulting in many WCs that mirror those encountered during transport. Recognising this overlap, for arrival and unloading, the opinion refers to a previous EFSA opinion on the transport of Equidae (EFSA AHAW Panel, 2022b).

The present scientific opinion emphasises the need to address all types of horses that may arrive at a slaughterhouse, considering their various origins, the management systems they have come from and how these may impact welfare outcomes during slaughter. This is detailed in Sections 3.1.2 and 3.1.3.

Among the methods used for stunning and killing horses worldwide, EFSA has applied the following criteria for the selection of methods to be included in this assessment:

1. all methods with described technical specifications known by the experts and not only the methods described in Council Regulation (EC) 1099/2009,

2. methods currently used for stunning and killing horses, and those still under development but likely to become commercially applicable and

3. methods for which the welfare aspects (in terms of welfare hazards, WCs, ABMs, preventive and corrective measures) are sufficiently described in the scientific literature.

The application of these criteria resulted in a list of stunning and killing methods and practices assessed in this Scientific Opinion. This may exclude less described methods.

All the methods for the slaughter of horses identified (penetrative captive bolt and firearms) are mechanical. The assessment will deal with each method separately. Although slaughter of horses without stunning might occur, there is no published scientific information about it and this practice is therefore not described in the present scientific opinion.

The mandate requests to define qualitative or measurable (quantitative) criteria to assess performance on animal welfare (ABMs). However, it is to be noted that in some circumstances, no ABMs exist or are feasible to use in the context of horse slaughter (e.g. measures for prolonged hunger at arrival).

This opinion proposes corrective measures for the identified hazards, which will prevent the WCs (e.g. correcting the temperature to prevent heat stress). Additionally, or when corrective measures for the hazards are not feasible, actions to mitigate the WCs are also discussed (e.g. showering horses in lairage to mitigate heat stress).

Lastly, the mandate requests a list of methods or practices deemed unacceptable on welfare grounds. These practices are discussed in a specific chapter. However, although scientific risk assessment can support discussions on what practices are unacceptable on welfare grounds, the ultimate decisions on acceptability involve other aspects (e.g. ethical and socio‐economic considerations) that need to be weighted by the risk managers together with welfare implications.

2. DATA AND METHODOLOGIES

2.1. Data

2.1.1. Data from literature

Information from the scientific publications selected as relevant from the literature search described in Section 2.2.2 and from additional literature identified by EFSA experts was used for a narrative description and assessment of each phase of the slaughter procedure (Phase 1 – pre‐stunning, Phase 2 – stunning and Phase 3 – bleeding).

2.1.2. Data from expert opinion

Data obtained from the literature were complemented by EFSA experts' opinion to identify hazards, hazard origin, WCs, ABMs, and preventive and corrective measures relevant to the current assessment.

2.2. Methodologies

2.2.1. Protocol

This scientific opinion follows the protocol detailed in the methodological guidance developed by the AHAW Panel in the context of the Farm to Fork strategy revision (EFSA AHAW Panel, 2022a).

The detailed protocol can be found in Annex A. In summary, EFSA experts described the phases and processes involved in the slaughter. For Phase 1, highly relevant WCs were identified through expert knowledge elicitation and hazards leading to the highly relevant WCs were listed, together with the related preventive and corrective measures and ABMs for assessing the WCs. For Phase 2 and Phase 3, hazards leading to the presence of consciousness or to the recovery of consciousness as well as preventive and corrective measures were identified.

2.2.2. Literature search

A literature search was carried out in peer‐reviewed and grey literature to identify hazards related to animal welfare during the slaughter of horses.

Restrictions were applied about the date of publication, considering only records published after the previous EFSA Scientific Opinion on the topic (EFSA, 2004). In addition, publications focused on transport aspects or on arrival at slaughter were excluded as they were already considered in the EFSA opinion on the transport of Equidae (EFSA AHAW Panel, 2022b). The key concepts of the latter applicable also to the slaughter context are briefly summarised when relevant to the present opinion.

Full details of the literature search and results are provided in Appendix A to this opinion.

In total, 15 references related to horse slaughter were retrieved and included in this assessment. In addition, EFSA experts complemented the information with references from review papers, book chapters and non‐peer‐reviewed papers that they considered relevant for the present assessment.

2.2.3. Expert knowledge elicitation

As described in Table A1 in Annex A, expert knowledge elicitation (EKE) was used for the sub‐questions requiring the identification of WCs, ABMs, hazards, and preventive and corrective (or mitigative) measures. Expert knowledge was mainly elicited via EFSA expert group discussion.

For the identification of highly relevant WCs for the processes of Phase 1, a semi‐formal EKE was carried out. The starting point was the list of 33 specific WCs identified by the AHAW Panel in the methodological guidance produced in the context of the F2F strategy revision. Out of these 33 WCs, the experts selected highly relevant WCs based on their individual estimates of duration, intensity and occurrence of the WC in each process (for details on the exercise see Appendix B). The semi‐formal EKE was performed for the following processes: (i) lairage, (ii) handling and moving and (iii) restraint. Only highly relevant WCs are further reported in this scientific opinion.

2.2.4. Structure of the opinion

Chapters are organised by slaughter phase. In Phase 1 (pre‐stunning), WCs are presented in a list and hazards are included within the related WCs. Within Phase 2, subchapters are organised by stunning methods and the focus is on pain and fear. Hazards are specifically listed per stunning method. Phase 3 refers to bleeding and describes the bleeding practice and related hazards.

2.2.5. Uncertainty analysis

The uncertainty in the assessment performed for this Scientific Opinion was investigated in a qualitative manner following the methods detailed in the EFSA guidance on uncertainty analysis in scientific assessments (EFSA Scientific Committee, 2018a, 2018b).

The EFSA experts agreed to tackle the uncertainty related to the methodology employed to identify WCs, ABMs and related hazards by describing the sources of uncertainty (Appendix C).

Regarding the overall impact of the identified uncertainties on the conclusions of the opinion, it was agreed to perform an assessment only for a subset of key conclusions that could be considered for risk management decisions (e.g. those on the application of the stunning methods).

Therefore, these conclusions have been reformulated into scientifically answerable assessment questions that expose the animals to a well‐defined scenario described in the conclusion. Then the resulting proportion of animals potentially affected by a given WC were judged against a reference quantity (rQ). The selection of rQ took into account the impact of the WC on the animals and what proportion of animals affected would encourage intervention. The rQ varies depending on the context of the conclusion.

For questions related to pre‐stunning, the experts were asked how certain they were that more than 20% of animals would experience a given WC. This 20% threshold was set as the cut‐off point above which measures should be taken to prevent or mitigate the WC, thereby ensuring that at least 80% of animals will not experience the WC.

Questions related to the stunning of animals were formulated so that experts would express their certainty that more than 99% of the animals are properly stunned (i.e. < 1% of the animals not effectively stunned and therefore being conscious). This threshold was chosen due to the critical level of pain and fear experienced by animals if not properly stunned before killing. In these conditions, having more than 1% of the animals ineffectively stunned was considered indicative of poor welfare.

Experts were then asked to express their certainty for each question according to three predefined agreed certainty ranges (Table 1) derived from the approximate probability scale in the guidance on uncertainty (EFSA Scientific Committee, 2018a, 2018b).

TABLE 1.

Three ranges used to express agreed (consensus) certainty around conclusions.

	Certainty range
Quantitative assessment	50%–100%	66%–100%	90%–100%*
Qualitative translation	From more likely than not to almost certain (summarised as ‘more likely than not’)	From likely to almost certain (summarised as ‘likely’)	From very likely to almost certain (summarised as ‘very likely’)

^*It is to be noted that this range encompasses the narrower range 99%–100% (almost certain, according to EFSA Scientific Committee, 2018a, 2018b). Conclusions for which the experts are almost certain (99%–100%) are flagged in the result section (chapter 3.8).

Experts were initially asked to individually select the certainty range that best reflected their degree of confidence for each conclusion considered. Then, a group discussion provided an opportunity for experts to present the rationale behind their assessments. A consensus was then sought to identify the range that best reflected overall certainty; if consensus could not be reached, the broader range encompassing all individual judgements was selected.

The exercise was not performed on the conclusions related to (a) arrival and (b) unloading (Phase 1 pre‐stunning), since these were derived from the opinion on the transport of horses (EFSA AHAW Panel, 2022b). The exercise was performed for conclusions related to (c) lairage, (d) handling and moving to the stunning area and (e) restraint.

3. ASSESSMENT

3.1. Introduction

Phase 1 includes the following processes (in chronological order): (a) arrival, (b) unloading from the vehicle, (c) lairage, (d) handling and moving to the stunning area and (e) restraint.

Horses are transported to reach the slaughterhouse, and upon arrival they might experience the WCs resulting from hazards they were subjected to during the transit phase. A dedicated scientific opinion on the transport of Equidae, recently prepared by EFSA (EFSA AHAW Panel, 2022b), describes hazards (e.g. separation from herd‐mates, forced closed proximity to unfamiliar and/or aggressive horses, forced adoption of an abnormal posture, extremes in temperature, water and feed withdrawal) and WCs occurring to horses during transit, loading and unloading. In that opinion, arrival is integrated into the description of the transit phase, as it is assumed that WCs experienced by the horses during transit will persist during arrival at destination.

3.1.1. Phases and processes assessed in the present Scientific Opinion

Table 2 shows a summary of the phases and processes, a short description of each and information about where the assessment can be found, i.e. whether it is dealt with in the present opinion or in the previous transport opinion (EFSA AHAW Panel, 2022b).

TABLE 2.

Summary of phases and processes assessed in this opinion.

Phase	Process	Description	Assessment
Phase 1 – pre‐stunning	Arrival	The period from the arrival of the vehicle at the slaughterhouse until initiation of unloading of the horses from the vehicle begins.	Covered in the transport of Equidae opinion under the transit phase (EFSA AHAW Panel, 2022b).
	Unloading	Unloading starts when the vehicle gate and ramp are opened and the first animal exits. Unloading ends when the last animal exits. In a slaughter context, unloading also includes moving animals to the lairage area.	Covered in the transport of Equidae opinion under the loading and unloading phase (EFSA AHAW Panel, 2022b).
	Lairage	Lairage is the period from the entry of the animals in the lairage area (after being unloaded from the vehicle) until initiation of handling and movement of the animals to prepare for stunning.	Covered in this opinion.
	Handling and moving	Moving horses from lairage to the stunning area.	Covered in this opinion.
	Restraint	Application to an animal of any practice designed to restrict bodily movements to facilitate effective stunning and bleeding.	Covered in this opinion.
Phase 2 – stunning	Stunning methods	Any intentionally applied method which causes loss of consciousness without pain, including any methods resulting in instantaneous death.	Covered in this opinion.
Phase 3 – bleeding	Bleeding	The process of exsanguination, intended to cause death.	Covered in this opinion.

3.1.2. Types of horses sent to slaughter

Horses can be kept as competition animals, companion animals, therapy animals, working animals on farm or for transport, as well as be farmed for meat or for milk (Fletcher et al., 2022). In addition, horses may live under wild or semi‐feral conditions (Minero & Canali, 2009). Horses from all these categories have the potential, unless specifically signed out of the food chain, to be slaughtered for human consumption (Bell et al., 2013). The functional category of horses will impact their capacity to be handled and manipulated by humans and their behavioural responses to slaughter.

Indeed, some horses stay unhandled, sometimes even with a total lack of exposure to human contact and unaccustomed to being moved or led (Riva et al., 2022), while others are fully halter‐trained and accustomed to transport and changes in living conditions (Leadon et al., 2008; Padalino, 2015; Waran et al., 2007).

Regarding terminology, in Council Regulation (EC) No 1/2005, ¹⁶ ‘unbroken equidae’ are defined as horses that cannot be tied or led by a halter without causing avoidable excitement, pain or suffering. The term ‘broken’ is used to indicate that a horse has been trained for riding or driving. In this scientific opinion, and similarly in the previous equine transport opinion (EFSA AHAW Panel, 2022b), the term ‘unhandled’ was used to indicate horses that cannot be tied or led by a halter without ‘causing avoidable excitement, pain and/or suffering’ and the term ‘handled’ was used to indicate horses that have been previously trained for being tied and led by a halter.

Unhandled horses will probably experience more handling stress during the pre‐stunning phase than handled horses.

Therefore, it is of importance to know the functional category of a horse before arriving at a slaughterhouse, to adapt how humans can approach the animal to induce the desired behaviour.

Besides the above‐mentioned functional categories, horses can also be divided into types based on:

• − Size: ponies are horses whose height at the withers is below 1.48 m without shoes and 1.49 m with shoes. Taller animals are categorised as horses.
• − Weight: saddle horses are commonly used for riding and weigh up to 700 kg. Draught horses are used for pulling carriages and usually weigh above 700 kg. Horses weighing less than 700 kg can pull carriages and horses above 700 kg can be ridden, but for simplicity, horses below and above 700 kg will be termed saddle and draught horses, respectively, in this scientific opinion. In this opinion, an average horse weight is considered to be 400 kg.
• − Age: a foal is a juvenile horse born the same year; a yearling is a young horse aged 1–2 years. Horses over 2 years of age are considered adults.
• − Anatomy: a mare is a female horse, a stallion is an intact male and a gelding is a castrated male, all above 2 years of age.
• − Destination: meat horses are the ones destined to be slaughtered for human consumption since their birth.

3.1.3. Background information on management systems

The background and experience of horses arriving at a slaughterhouse reflect a variety of husbandry conditions in which horses are kept and their previous experience with humans. The husbandry conditions can range from extensive systems to high‐density group housing (Insausti et al., 2021; Raspa et al., 2020a, 2020b) or fully stabled horses kept either in single boxes (for example racehorses) or in group under a shelter (Hartmann et al., 2015). In addition, horses may be kept in part stabled/part pastured conditions (Mills & Clarke, 2007). The premises can range from small private yards to large commercial enterprises. Another set of animals constitutes the ‘semi‐feral’ group. These animals roam free in large areas, live on pasture or other natural habitats and are only gathered at specific times of the year, if at all (Mendonca et al., 2022; Fletcher et al., accepted for publication).

3.2. Phase 1: Pre‐stunning

3.2.1. Highly relevant WCs identified for phase 1 (pre‐stunning)

The highly relevant WCs occurring to horses during Phase 1 (pre‐stunning) were identified via EKE (see Section 2.2.3) and are presented (marked with a Y) in Table 3 below.

TABLE 3.

Welfare consequences identified as highly relevant for Phase 1 – pre‐stunning.

Phase 1: Pre‐stunning
	Arrival (covered in the EFSA transport opinion under the transit phase)	Unloading (covered in the EFSA transport opinion under loading and unloading phase)	Lairage	Handling and moving to the stunning area	Restraint
Welfare consequence (WC)
Gastro‐enteric disorders	Y
Group stress	Y		Y
Handling stress		Y		Y
Heat stress	Y	Y	Y
Injuries (bones, joints, skin, muscles) a	Y	Y	Y	Y	Y
Prolonged hunger	Y		Y
Prolonged thirst	Y		Y
Respiratory disorders	Y
Resting problems	Y		Y
Restriction of movement	Y	Y	Y	Y	Y
Sensory under or over stimulation		Y	Y	Y	Y
Separation stress			Y	Y

^a In the EFSA guidance (EFSA AHAW Panel, 2022a) this WC was further specified as two separate WCs, (i) soft tissue lesions and integument damage and (ii) bone lesions. However, these two WCs will have the same hazards, preventive and corrective measures. For this reason, to avoid repetition of text, they will be presented under the common term ‘Injuries’.

Some WCs may persist throughout the whole Phase 1 (e.g. gastro‐enteric disorders) but in the context of slaughter they were considered as highly relevant only in one process (e.g. arrival for gastro‐enteric disorders) because in the following processes other WCs are more relevant.

Conversely, some WCs (e.g. restriction of movement) are present across multiple processes, as they arise from different hazards encountered at each process and are therefore consistently considered highly relevant.

3.2.2. Arrival

3.2.2.1. Description of arrival

Arrival is the period from the arrival of the vehicle at the slaughterhouse until initiation of unloading.

The same WCs that horses experience during transit will persist at arrival, namely during the period that the horses spend in the stationary vehicle, and some of these WCs (e.g. prolonged hunger and thirst, restriction of movement) will progressively be exacerbated the longer the animal stays in the vehicle. However, there is no published information regarding the average or maximum time horses typically spend in the stationary vehicle at arrival.

The assessment of the arrival in the present opinion is limited to a summary of the main conclusions and recommendations per each WC, as any preventive measures should be applied before transport. A detailed description of hazards and preventive or mitigating measures can be found in the ‘Welfare of Equidae during transport’ opinion (EFSA AHAW Panel, 2022b).

3.2.2.2. The highly relevant WCs identified for arrival

The previous EFSA opinion on the transport of horses (EFSA AHAW Panel, 2022b) identified, based on severity, duration and frequency of occurrence, eight highly relevant WCs during transit that persist at arrival. Their definitions are reported in Table 4.

TABLE 4.

Highly relevant welfare consequences identified during transit and persisting also at arrival and their definitions (EFSA AHAW Panel, 2022a).

Welfare consequence	Definition
Gastro‐enteric disorders	The animal experiences negative affective states such as discomfort, pain and/or distress due to impaired function or lesions of the gastrointestinal tract (resulting e.g. from nutritional deficiency, infectious, parasitic or toxigenic agents).
Heat stress	The animal experiences stress and/or negative affective states (such as discomfort and/or distress) due to exposure to high effective temperatures.
Injuries	The animal experiences negative affective states (such as pain, discomfort or distress) due to physical damage to somatic tissues (bones, joints, skin, muscles).
Prolonged hunger	The animal experiences craving or urgent need for feed or a specific nutrient, accompanied by a negative affective state, eventually leading to a weakened condition if metabolic requirements are not met.
Prolonged thirst	The animal experiences craving or urgent need for water, accompanied by an uneasy sensation (a negative affective state), eventually leading to dehydration if metabolic requirements are not met.
Respiratory disorders	The animal experiences negative affective states (such as discomfort, pain, air hunger and/or distress) due to impaired function or lesions of the lungs or airways.
Resting problems	The animal experiences stress and/or negative affective states (such as discomfort and/or frustration) due to the inability to lie/rest comfortably or sleep (e.g. due to hard flooring). The severity of resting problems is expected to increase with time and may eventually lead to fatigue.
Restriction of movement	The animal experiences stress and/or negative affective states (such as pain, fear, discomfort and/or frustration) because it is unable to move freely or is unable to walk comfortably (e.g. due to overcrowding, unsuitable floors, being tethered or confined individually in stalls).

A summary of information per each of these WCs is reported from the EFSA opinion on transport (EFSA AHAW Panel, 2022b) below.

Gastro‐enteric disorders

The WC ‘gastro‐enteric disorders’ is considered highly relevant in the transit stage and therefore can persist upon arrival. Several factors, other than journey duration, can contribute to this WC, specifically transportation stress and changes in the feeding regime (possible pre‐transport fasting plus time off feed during transport). Transport without feed and water for 12 h increases the risk of gastric ulceration (Padalino et al., 2020). Preventive measures for gastro‐enteric disorders are listed in the EFSA opinion on transport of horses (EFSA AHAW Panel, 2022b).

The mitigation measure at arrival for an animal showing signs of a gastro‐enteric disorder is immediate unloading and slaughter.

Heat stress

Ambient temperature influences the heat load placed on the animals. The temperature inside a vehicle is affected by several factors: outdoor temperature, humidity, solar radiation, stocking density (due to heat and moisture from the animals), heat loss from the vehicle, vertical height, placement of compartment partitions inside the vehicle, vehicle type, presence and type of forced ventilation and several others. However, due to the complexity of such conditions, as well as the strong evidence for the effect of humidity on heat stress, when animal welfare during transport and at arrival is evaluated, at least the combined effects of temperature and humidity should be taken into account. The thermal comfort zone (TCZ) (EFSA AHAW Panel, 2022b) is the ambient temperature interval in which the energetic and physiological efforts of thermoregulation are minimal, and the animal is in the preferred or chosen thermal environment. When the ambient temperature is above the animals' TCZ, high humidity will reduce evaporative heat loss, resulting in an increased risk of heat stress. Based on the commencement of evaporative heat loss and sweating rates, the upper threshold of the TCZ for horses is suggested to be approximately 20°C.

The upper critical temperature describes the threshold above which an animal must significantly increase physiological mechanisms to prevent body temperature to raise above the physiological range (i.e. any increase in metabolic rate or heat production, or a significant increase in the rate of sweating). Based on the initiation of heat production above baseline levels and the increase in the rate of sweating, the upper critical temperature for horses is estimated to be approximately 25°C (Morgan et al., 1997). This will vary somewhat depending on the individual horse conditions, the breed and the degree of acclimatisation to heat.

As prevention, a temperature inside vehicles not exceeding the upper critical temperature of 25°C (dry‐bulb temperature) can reduce the risk of heat stress.

Regarding mitigative measures, parking the vehicle in a shaded area at arrival, where ventilation is ensured or with forced ventilation (e.g. fans) turned on, might mitigate heat stress. In addition, removing from the vehicle any horse showing signs of heat stress, placing the horse in the shade, providing a cold shower and drinking water are further mitigation measures (Brownlow et al., 2016).

Injuries

At arrival, injuries may result from hazards occurring during transport (e.g. lack of bedding, slippery floors, unsuitable vehicles, rough driving, orientation inside the vehicle, lack of space, lack of staff training, mixing of unfamiliar horses) (Miranda‐de la Lama et al., 2020; Padalino et al., 2023). In addition, further injuries may occur at arrival if horses remain in the vehicle and the unsuitable conditions described above continue (Marlin et al., 2011). Horses being aggressive towards conspecifics may injure themselves and others by kicking and/or biting.

Preventive measures can be applied before transport (EFSA AHAW Panel, 2022b) and are listed below, as they will impact the WCs at arrival:

• Use of recommended stocking density during transport (less than 200 kg/m² ‐ see later under ‘restriction of movement’);

• use of loose transportation for a small group of familiar conspecifics of horses showing signs of not being able to be tied or led by a halter;

• maintenance of a suitable floor surface and provision of fresh bedding;

• securing partitions in the vehicles;

• separation and transport in individual stalls of dominant and aggressive horses (e.g. stallions);

• use of trained staff to move horses.

A mitigation measure is unloading animals that are injured as soon as possible or performing emergency slaughter on the vehicle if a horse cannot be unloaded without causing severe pain.

Prolonged hunger

The WC prolonged hunger is regarded as highly relevant in the transit stage and therefore at arrival. The duration of prolonged hunger depends on the time since the last meal and the possibility of eating in transit. If this is not possible, the severity is expected to increase with increasing transport duration. At some point in time, the need for feed becomes problematic for the animals. Prolonged hunger may lead to exhaustion and a weakened condition. Physiological changes indicative of hunger can be present after 12 h from the last meal (EFSA AHAW Panel, 2022b). The staff is the main origin of this hazard, leaving horses without access to feed (on‐farm and/or during transport) for too long.

Preventive measures apply before and during transport (see EFSA AHAW Panel, 2022b). At arrival, the mitigation measures are immediate slaughter upon arrival or provision of feed in lairage, if the expected time off feed is longer than 12 h.

Prolonged thirst

The WC prolonged thirst is considered highly relevant in the transit stage and therefore at arrival. The prevalence may be high if water is not provided to the animals or for some reason (e.g. high stocking density, lack of familiarity, neophobia or fear of other animals), they are not able to drink enough water. Although some horses may not drink while the vehicle is in motion, many will drink during a journey break if water is available in the vehicle. Depending on factors, such as time off water before departure and/or microclimatic conditions before and during the journey, horses may not be thirsty during the initial phase of the transit stage, but thirst will develop over time if water is not provided or accessible. The duration of prolonged thirst depends on accessibility of water and journey duration, and severity is expected to increase with increasing journey duration, as the need for water becomes problematic for the animals. Prolonged thirst may lead to dehydration, discomfort and suffering. The available data do not allow a detailed assessment of the interval between journey start and initiation of thirst. Haematological changes indicative of mild dehydration have been observed after journeys of 1 and 3 h without water at temperatures within the thermal comfort zone. Behavioural indicators of increased thirst were observed after a 3‐h journey (Tateo et al., 2012).

Preventive measures apply before and during transport (see EFSA AHAW Panel, 2022b). At arrival, the mitigation measures are immediate unloading and provision of water in lairage or immediate slaughter.

Respiratory disorders

Respiratory disorders mainly result from restrictive tying practices experienced during transport (when horses are tied too tight, for instance with a rope shorter than 60 cm, they cannot lower their head below the whither height and clear the respiratory tract). Respiratory disorders can be severe, with detectable clinical signs after journeys of 10–14 h (EFSA AHAW Panel, 2022b).

Preventive measures apply before and during transport (see EFSA AHAW Panel, 2022b). At arrival, the mitigation measure is immediate slaughter upon arrival.

Resting problems

Resting problems are considered as a highly relevant WC in the transit stage and may continue at arrival. During transit, the occurrence is expected to be high, as horses will not lie down or be able to adopt the tripodal resting position due to the need to continuously make postural adjustments to compensate for vibration and acceleration changes. Resting problems may occur throughout the journey, likely with cumulative effects, potentially leading to fatigue and, eventually, exhaustion.

Due to lack of knowledge, it is not possible to estimate a temporal cut‐off after the initiation of transit for the onset of this WC.

Preventive measures apply before and during transport (see EFSA AHAW Panel, 2022b).

Regarding mitigation, possible measures are: unloading without delay of horses showing signs of severe resting problems, allowing horses to rest in lairage or immediate slaughter (Padalino et al., 2023). In extreme cases (the so called ‘downers’), the animal might have to be stunned and killed in the vehicle.

Restriction of movement

During transport, horses are placed in a restricted space, either because they are confined in individual stalls using partitions or due to the pressure on individual space exerted by other loose horses within the group. At arrival, restriction of horse movement result from the space allowance during the transport. Restriction of movement would also result from inappropriate use of halters or ropes when individual horses are tied during transport.

Lateral space is necessary for spreading the legs to balance and adopting the excretory posture.

Low vertical space can be associated with restriction of movement due to the lack of ability to move around and lack of space for natural movements, in particular of the head.

Front and back spaces are necessary for lowering the head to balance, for resting and clearing airways, with additional space possibly required to accommodate feeders and drinkers in the vehicles.

For horses transported in individual stalls, it was suggested that an additional space of at least 20 cm at either side (40 cm more in total) of the body of a horse measured at the widest point prevents restriction of movement (EFSA AHAW Panel, 2022b).

When transported individually, the biomechanics involved in changing head posture suggest that a free space of 20 cm both in front and behind the horse (a total of 40 cm), measured when the horse is standing with the neck parallel to the ground, will allow the animal to lower the head for balancing, resting and clearing airways.

For horses transported in groups, limited available evidence (implying significant uncertainty) suggests that a stocking density of less than 200 kg/m² leads to improved welfare compared to higher stocking densities (EFSA AHAW Panel, 2022b).

Regarding vertical space, no studies have established a proper deck height for horses during transport. Earlier it has been recommended that the minimum internal height of the compartment should be the height of the withers of the tallest animal in a compartment +75 cm. However, the lack of evidence‐based thresholds constitutes a gap in knowledge (EFSA AHAW Panel, 2022b).

Preventive measures apply during transport (see EFSA AHAW Panel, 2022b). At arrival, if animals are experiencing restriction of movement (e.g. caused by stocking density higher than 200 kg/m²), the mitigation measures are immediate unloading upon arrival or provision of sufficient space in lairage (see Section 3.2.4.2).

3.2.3. Unloading of horses from the vehicle

3.2.3.1. Description of unloading

Unloading starts when the vehicle gate and ramp are opened, and the first animal exits the vehicle and ends when the last animal exits. Horses are released from the single or group compartments within the transport vehicle. Handled horses will be led, one by one, down the ramp to the place of destination (lairage or stunning area). Unhandled horses will self‐unload one after the other and will be driven as a group to their destination. Ante‐mortem inspection can be carried out at unloading, otherwise it is done in lairage.

3.2.3.2. Highly relevant WCs identified for unloading

The highly relevant WCs identified for the unloading stage (EFSA AHAW Panel, 2022b) are reported in Table 5 with their definitions.

TABLE 5.

Highly relevant welfare consequences identified during unloading and their definitions.

Welfare consequence	Definition
Handling stress	The animal experiences stress and/or negative affective states (such as pain and/or fear) resulting from human or mechanical handling (EFSA AHAW Panel, 2022a).
Heat stress	See definition in Section 3.2.2.2 (Table 4)
Injuries	See definition in Section 3.2.2.2 (Table 4)
Restriction of movement	See definition in Section 3.2.2.2 (Table 4)
Sensory overstimulation	The animal experiences stress and/or negative affective states (such as fear and discomfort) due to visual, auditory or olfactory overstimulation by the physical environment (EFSA AHAW Panel, 2022a).

A summary of information per each of these WCs is reported from the EFSA opinion on transport of horses (EFSA AHAW Panel, 2022b) below.

Handling stress

The hazards leading to handling stress during unloading depend on the handler, the previous training of the horse for transport‐related practices and the facilities (i.e. the ramp).

During unloading, in case of lack of habituation to the relevant handling, most horses are expected to experience handling stress, which may be associated with fear and may lead to distress or injuries.

Preventive measures include a high level of experience and training of the handler, sufficient time for the handler to ensure calm and correct unloading and adequate unloading facilities (i.e. complying with the requirements for ramp slope – see under ‘injuries’ – and providing non‐slippery floors).

Inexperienced horses benefit from being handled very calmly and allowed more time to adjust to the surroundings.

As a mitigation measure, if it is not possible to unload a horse calmly by itself, another horse could be unloaded first and used as a demonstrator.

Heat stress

Numerous hazards can induce heat stress during unloading, including high effective temperature and prolonged unloading time.

Measures to prevent the risk of heat stress include planning the journey to avoid any delays in unloading. Mitigation measures include parking the vehicle in the shade or in an area where ventilation is ensured or leaving forced ventilation on while animals are in the vehicle.

Injuries

During unloading horses can get injured (e.g. open wounds, broken bones, bruises), for example when slipping and falling, bumping into hard surfaces or trapping their limbs into the equipment or facilities.

Several hazards can lead to injuries during unloading: level of training of the horse, unsuitable vehicles and facilities and inappropriate handling of the horse by the handler (Roy et al., 2019).

The transport vehicle is an important source of traumatic injuries in transported horses (Cregier & Gimenez, 2015). These can result from projections and obstacles associated with the unloading ramp or auditory stimuli frightening the horses.

Measures to prevent injuries during unloading include ensuring that unloading is performed by experienced and knowledgeable handlers, that inappropriate handling instruments (e.g. sticks, electrical prods) are not used, that the unloading is performed in a location with as little disturbance as possible, and that the facilities are appropriate and well‐maintained (i.e. without broken or protruding parts, without gaps).

In addition, an appropriate unloading ramp can prevent injuries, i.e. a ramp not too steep, < 20°, fitted with a system such as provided by foot battens to facilitate foothold, with side barriers, stable and not noisy when used. Covering the ramp with straw, sand or sawdust can prevent slipping and reduce noise.

As a mitigation, if horses show signs of movement restriction, the existing unloading facilities (e.g. ramp, side panels) can be upgraded and proper unloading can be restarted, after allowing the horses to calm down.

Restriction of movement

The hazards leading to restriction of movement during unloading are poor unloading facilities, inappropriate tools (e.g. rugs, short lead rope), inappropriate handling or inexperienced handlers. Similar preventive and corrective actions to injuries apply to restriction of movement.

Sensory overstimulation

Horses get easily agitated in unfamiliar situations. Various auditory, visual and unfamiliar sensory stimuli can lead to sensory overstimulation during unloading.

According to Grandin et al. (1999) horses can become highly fearful and agitated when suddenly exposed to anything novel. Even a handled horse that is habituated to being exposed to novel situations may rear, bolt or kick if frightened by a suddenly occurring novel stimulus. Similarly, horses may refuse to walk over a shadow, puddle or bright spot of sunlight which may be present during unloading.

To prevent sensory overstimulation due to auditory stimuli, the measure is avoiding shouting or loud auditory stimuli from equipment or other animals (i.e. dogs barking) during unloading. To avoid excessive visual stimuli, avoiding light contrasts and shadows as much as possible and providing comparable levels of light in the inner part of the animal compartment on the vehicle and in the unloading facilities are possible measures, as well as training handlers on the flight zones and how to approach horses.

Similarly, avoiding olfactory stimuli that are unfamiliar to horses in the unloading areas can prevent sensory overstimulation.

The mitigation measure, if a horse is reluctant to unload and shows signs of sensory overstimulation, is to check the area to identify and remove possible stressors (such as auditory stimuli, unfamiliar/aversive olfactory stimuli or visual disturbances).

3.2.4. Lairage

3.2.4.1. Description of lairage

After unloading, horses are led to a lairage area before being moved to the stunning zone. Animals can be housed in pens at different group sizes. They can also be tied or kept individually in boxes or stalls.

Lairage can be used for ante‐mortem inspection by the official inspectors. Lairage is also used by the business operator to keep a pool of animals and maintain a constant slaughter rate. It also provides an opportunity for animals to rest and recover from the WCs experienced during transport. This recovery can occur only when animals are provided with enough space, adequate ventilation, a quiet environment (FAWC, 2003) and water.

Lairage conditions per se can have an impact on the welfare of horses and if unsuitable they can exacerbate the WCs originating from the hazards horses have previously been exposed to.

There is no published information regarding the average or maximum time horses currently spend in lairage.

3.2.4.2. Highly relevant WCs identified for lairage

The highly relevant WCs occurring to horses during lairage were identified via EKE (see Section 2.2.3) and are presented in Table 6 with their definitions.

TABLE 6.

Highly relevant welfare consequences identified during lairage and their definitions.

Welfare consequence	Definition
Group stress	The animal experiences stress and/or negative affective states (such as pain, fear and/or frustration) resulting from a high incidence of aggressive and other types of negative social interactions, often due to hierarchy formation and competition for resources or mates (EFSA AHAW Panel, 2022a).
Heat stress	See definition in Section 3.2.2.2 (Table 4)
Injuries	See definition in Section 3.2.2.2 (Table 4)
Prolonged hunger	See definition in Section 3.2.2.2 (Table 4)
Prolonged thirst	See definition in Section 3.2.2.2 (Table 4)
Resting problems	See definition in Section 3.2.2.2 (Table 4)
Restriction of movement	See definition in Section 3.2.2.2 (Table 4)
Sensory overstimulation	See definition in Section 3.2.2.2 (Table 4)
Separation stress	The animal experiences stress and/or negative affective states (such as fear and/or frustration) resulting from separation from conspecifics (EFSA AHAW Panel, 2022a).

A summary of information retrieved from literature complemented by expert opinion per each of these WCs is presented below.

Group stress

When horses are housed in a group in lairage, conflicts with pen mates and the inability of subordinate animals to escape the dominant ones can lead to group stress. In addition, fighting within the group can lead to injuries and resting problems.

Two main hazards lead to group stress in lairage: mixing of unfamiliar animals and inadequate resource allocation.

Regarding mixing of unfamiliar animals, specific evidence is lacking for horses in the lairage area, but it is known that mixing groups disturbs the social cohesion between horses in the original groups (Van Dierendonck & Spruijt, 2012) and may result in fighting (i.e. biting and kicking) to establish a new social hierarchy, especially in groups transported loose (Houpt & Wickens, 2014). Stallions are prone to fight when they are housed together.

The EFSA experts suggest that, similarly to horses during transport, mixing of unfamiliar animals (especially stallions) in the lairage area increases the risk of aggressive interactions resulting in group stress.

A preventive measure is to avoid mixing unfamiliar animals or keep familiar animals together from farm to slaughter, and to separate stallions in different pens or use single pens.

Inadequate resource allocation occurs when there are insufficient resources, or resources are not distributed in a way so that all horses can access them. For instance, when water is not accessible to all horses at the same time, animals might fight for access or some individuals may monopolise resources, leading to group stress.

When animals are housed in groups, measures to prevent group stress are: providing enough space to allow animals to escape aggressive interactions, and distributing resources (e.g. water) evenly and in an accessible way to all animals.

Mitigation measures when a horse shows signs of group stress include housing the horse individually, or slaughtering horses that arrive at the slaughterhouse after being transported as part of a group of unfamiliar individuals, immediately after unloading.

Heat stress

In the lairage area, temperature variation can be large and depends on the time of the day, the season, the ventilation equipment and the insulation of the lairage zone.

At lairage, a too‐high effective temperature (exceeding the upper critical temperature of 25°C) and inadequate ventilation may lead to heat stress, comparable to what is described during transport (EFSA AHAW Panel, 2022b) and at arrival (see Section 3.2.2.2).

However, other factors influence heat stress as well, such as humidity and duration of exposure to high effective temperatures.

Furthermore, insufficient space allowance can lead to heat stress in hot weather and prevent animals from resting owing to interference from their conspecifics (Weeks, 2008). Low space allowance increases the number of horses in a given compartment, and thus the overall production of metabolic heat and moisture (EFSA AHAW Panel, 2022b). Unless this extra metabolic heat and moisture can be effectively removed by natural or forced ventilation, it can be detrimental at high temperatures and high humidity, and predispose the animals to heat stress, causing discomfort and potentially leading to distress.

High stocking densities in lairage pens might result in increased aggressive interactions. Aggressive interactions in lairage pens will exacerbate the risk of heat stress in horses (Roy et al., 2015a, 2015b). Therefore, insufficient space allowance may exacerbate heat stress.

Similarly to arrival, the preventive measure for heat stress is the maintenance or adjustment of the temperature, e.g. through ventilation, so that the upper critical temperature of 25°C is not exceeded (see Section 3.2.2.2).

If signs of heat stress are identified, showering can be applied to mitigate the WC.

Sprinklers (including misting) and fan cooling (forced ventilation) systems in enclosed lairages have been shown to be effective for other species (e.g. cattle under shaded housing, Collier et al., 2006). Such systems might be adapted to lairage areas, but it should be considered that evaporative cooling methods may have a limited efficiency if the humidity is high. Also, it is important not to induce panic reactions by showering or misting untrained horses. Forced ventilation in enclosed lairage areas or high headspace in outdoor lairages may be required to avoid the build‐up of humidity at the animal level. It is also worth noting that misting devices installed at the roof level may be more effective in removing the hot air rising from the animals and accumulating under the ceiling. On the contrary, sprinklers are usually provided at the animal level to wet the bodies and achieve effective evaporative cooling.

For field lairages, a preventive measure is to provide shade (e.g. trees) or shelters.

Provision of good ventilation and access to clean water or immediate slaughter are the mitigation measures.

It may be advantageous to provide additional space to the animals (see Section 3.2.4.2 for recommended space in lairage). However, no studies were identified providing specific quantitative information on the appropriate space allowances for horses in relation to thermal conditions.

Injuries

Improper design, construction and maintenance of premises is an important hazard that may lead to injuries at lairage. Features related to pen design or poor maintenance (e.g. broken gates and metal parts), exposure to hard, abrasive or slippery surfaces, poorly designed, constructed and located drainage systems and water troughs can result in injuries.

Lairage pen fences not high enough (i.e. above the withers, e.g. 1.8 m) increase the risk of horses escaping and getting injured. Furthermore, pen fences that are not made of solid partitions of at least 1 m height (Interbev, 2019, see Figure 1 under separation stress) from the floor increase the likelihood of getting injured (e.g. trapping their feet when kicking or pawing).

FIGURE 1.

Example of suitable pen with a partitions consisting of a solid lower part for 1 m and an open upper part built with tubular railings (©Interbev).

Preventive measures include proper design, construction and maintenance of lairage facilities to suit the species‐specific behaviour of horses. The provision of sufficiently high pen fences and partitions (e.g. 1.8 m) including a lower solid part can prevent the risk of injuries. Regular cleaning of the lairage facility is essential to prevent WCs due to slipping and falling. Positioning of water troughs alongside walls rather than in the middle of the pen helps to prevent horses from stumbling and injuring themselves. For example, Gibbs and Friend (2000) reported that, in transported horses, adequate manoeuvring room was available so that all of the horses could get access to water when the water troughs were placed on both sides of a compartment rather than in the middle. The EFSA experts consider that, similarly, in the lairage pen a drainage system positioned along the walls rather than across the pen prevents injuries from horses trapping their feet.

Mixing unfamiliar animals or placing stallions together or mixed with mares or geldings is another important hazard that may result in aggressive behaviour and fights at lairage (see also group stress above). Biting and kicking may result in serious wounds and other injuries.

Even familiar animals may fight when put together in a space that cannot allow them to keep inter‐individual distances. Competition for resources (space, access to water), especially after long journeys, will lead to aggression.

Preventive measures include keeping familiar animals together, avoiding mixing unfamiliar horses, and separating aggressive horses and stallions in individual pens.

Mitigation measures include the removal of aggressive animals or the slaughter of mixed groups immediately after unloading.

Lastly, in lairage unexpected loud noises are hazards that may cause animals to panic and injure themselves or pen mates. Noise can be due to vocalisations of animals, people shouting or equipment (e.g. metal gates, air compressors). This can be prevented by avoiding shouting or banging paddles or gates and reducing noise from equipment.

Low space allowance in lairage may also result in injuries and preventive measures are indicated later in this chapter under ‘restriction of movement’.

Prolonged hunger

At the entry in lairage, animals still experience the level of hunger and thirst that they were experiencing upon arrival. During lairage, animals are commonly provided with water. They are not usually provided with feed, however, in accordance with Council Regulation (EC) 1099/2009, it is mandatory to feed animals if they are not going to be slaughtered within 12 h from their arrival.

The EFSA experts suggest that the identified preventive measures for prolonged hunger are slaughtering the animals without delay or, providing access to feed if horses are expected to stay in lairage for long, i.e. if the total time from the last meal is more than 12 h. This last figure is aligned with the recommendations from the EFSA horse transport opinion, considering the time period from feed withdrawal (EFSA AHAW Panel, 2022b) and not from arrival at slaughter.

Prolonged thirst

During transport, animals usually do not have water available, which might lead to dehydration and prolonged thirst. In lairage, thirst should be mitigated by allowing the animals to drink and water must be available, according to Council Regulation (EC) 1099/2009.

In case water is not provided or the construction of the drinking point is inappropriate (e.g. preventing horses from easily accessing clean water), horses will experience dehydration (Roy et al., 2015c).

Preventive measures include the provision of a watering system familiar to the animals, designed and constructed to allow all animals easy access to water at any time, without being injured or limited in their movements, providing clean water and minimising the risk of water contamination with faeces.

Resting problems

Resting problems in lairage mainly result from hazards leading to the impossibility to rest properly and in particular, as described for the arrival, from insufficient space allowance, lack of bedding and negative interactions between horses (see group stress).

Space allowance given to horses should be sufficient for them to rest, get up, turn around and access resources (such as water) without hindrance. Horses usually rest during the day by adopting a tripodal position that they keep unless they are forced to move (e.g. bumped in by another horse). If they are very tired, they might want to lie down to sleep but this requires that the horse is calm and feels safe. In overall resting in lairage will most of the time be satisfied by a tripodal, undisturbed position.

In other livestock species (e.g. cattle), space allowances are estimated using the allometric equation for space allowance:

$$\text{space allowance}\left({\mathrm{m}}^2/\text{animal}\right)\mathrm{A}={\mathrm{kW}}^{2/3}$$

where k is a constant and W represents live weight in kilograms (Petherick and Phillips, 2009).

However, no k‐value has been developed or validated for horses. Therefore, it is not possible to indicate the appropriate space allowance for horses based on an allometric equation.

On average a horse can fit in a rectangle of 2.4 m by 0.75 m (EFSA AHAW Panel, 2022b). For an average horse of approx. 400 kg this physical space corresponds to a stocking density of 220 kg/m².

The EFSA experts suggested that adequate space allowance at lairage in collective pens is provided when between one and another horse there is room for at least the length and width of a standing horse. That would allow horses to adopt the tripodal position to rest comfortably and access resources (such as water). This equates to approximately 50% of free space in the pen, regardless of the size of the animals. When 50% of space is not free in the pen, the horses might experience resting problems.

Therefore, considering the need to have 50% of free space in the pen, a stocking density exceeding 110 Kg/m² might lead to resting problems in lairage.

When horses are kept in individual stalls or boxes at lairage, the minimum space should be equivalent to that recommended for arrival (EFSA AHAW Panel, 2022b). Therefore, if a free space of less than 40 cm in addition to the body width and less than 40 cm in addition to the body length is provided in the stall, the horse will experience resting problems.

The preventive measure is to provide enough horizontal space to rest, e.g. in a tripodal position, get up, turn around and access water (i.e. stocking density less than 110 Kg/m²).

Another hazard for resting problems is the lack of bedding. In accordance with Council Regulation (EC) 1099/2009, when animals are expected to stay in the slaughterhouse for more than 12 h after arrival, they should be provided with suitable bedding in lairage pens. The bedding material absorbs urine and faeces and improves comfort of the horses, facilitating resting.

Regarding mitigation measures, individuals showing signs of severe resting problems, fatigue and/or exhaustion in lairage should be slaughtered immediately.

Restriction of movement

Restriction of movement in lairage occurs when there is no sufficient space to get up, move around and access resources. The hazard is the improper design, construction and maintenance of the area, related to the space, but also to floor materials and features.

Horizontal space needs have been described above under resting problems.

Vertical space is also important at lairage. Low vertical space is associated with reduced ventilation, reduced ability to move around and lack of space for natural movements (e.g. raising the head). No studies have established a proper height for the pens in lairage for horses, however DEFRA Code of Practice for horses (DEFRA, 2013) recommends that stables for horses should have ‘roofs high enough to provide adequate ventilation including good air circulation. Additionally, space is needed for horses to raise their head, especially during interaction with other animals. There should be a minimum clear space to the eaves of 60–90 cm above the ears of the horse in its normal standing position’.

The latter indication from DEFRA corresponds to an overall floor‐to‐ceiling height comprised in a range of 2.7–3.3 m in lairage. The EFSA experts consider that a vertical height of less than 2.7 m can lead to restriction of movement in lairage pens for horses (average horses, as defined in 3.1.2) due to the impossibility of raising the head and rearing especially during interaction with other animals.

Another hazard leading to restriction of movement in lairage is when the solid partition between pens is not high enough leading to the risk of horse’ feet being trapped in non‐solid partition.

Horses slaughtered for human consumption are mostly killed in cattle slaughterhouses. There is no guidance on how to adapt the existing cattle facilities to suit the handling, movement and slaughter of horses (European Commission, 2018), for example regarding the appropriate height of partitions and fences in lairages, materials and structure of the floor that could be used in lairage pens to accommodate horses. Information regarding how to manage in lairage horses of very different size, weight and background (related to previous management) is also lacking.

Preventive measures include proper design, construction and maintenance of lairage facilities. In particular, the factors to be considered are:

• appropriate height of the ceilings (i.e. > 2.7 m);

• solid floor, smooth, non‐slippery, with no puddles and with an adequate slope for water and urine evacuation;

• location of drains on the sides of the passageways and pens to reduce baulking and use of drain covers to prevent animals from trapping their feet;

• reducing lighting variations (e.g. on the floor) so that animals can move easily.

Corrective measures include surveillance for overcrowding and provision of extra floor space (by removing animals from overstocked pens) and the required structure of the pen The mitigation measure is to proceed to slaughter as soon as possible in case animal welfare is severely impaired.

Sensory overstimulation

Since the lairage area is inside the slaughterhouse, horses can be subjected to different levels of visual, auditory and olfactory stimuli.

The same hazards that may lead to sensory overstimulation at unloading also apply to lairage (see Section 3.2.3.2).

Preventive measures for auditory overstimulation include the reduction of sudden noises, for instance vocalisation of animals, equipment noises (air compressors, air curtains, fans) and any shouting or banging of paddles. In addition, the Animal Welfare Council of the United Kingdom (Farm Animal Welfare Council, 2003) has recommended the separation of the lairage from the other areas (i.e. stunning or unloading area) either by space or a soundproof wall or partition and, as concerns gates, a ‘non‐slam’ culture should be adopted to prevent noise at lairage. According to the European Commission (2017), to prevent sensory overstimulation the noise level in the lairage area should not be above 75dB for more than 5 consecutive minutes.

Preventive measures for visual overstimulation include the provision of uniform and diffuse lighting, with a sufficient level to enable inspection (for example, at 200 lux), provision of dim lighting to facilitate resting, prevention of light reflections (e.g. from walls, pools of water, metal objects, or the clothes and caps of operators), use of dark colours for all structures, equipment and protective clothing.

At the slaughterhouse, horses may perceive odours as dangerous signals (Micera et al., 2010, 2012). Preventive measures for olfactory overstimulation include, cleaning the pens between different batches and avoiding using pens where other animal species have been kept without cleaning act as preventive measures. The application of a mentholated ointment on the nostrils has been shown to limit the olfactory perception. Another important measure is the provision of a ventilation rate sufficient to control levels of toxic or irritant gases, such as carbon dioxide and ammonia (Weeks et al., 2012).

Separation stress

Horses housed individually may experience separation stress. As prevention, they will benefit from visual contact with other horses. This can be achieved by using, in case of individual housing, pen partitions high enough to ensure safety as described above under injuries/restriction of movement but still allowing visual contact with conspecifics.

An example of a suitable pen is presented below in Figure 1 (Interbev, 2019), where the partition presents a solid lower part that is at least 1 m high and an upper part made by tubular railings up to above wither height (i.e. 1.8 m).

In addition, separation of mares and unweaned foals can provide considerable stress to both the mare and the foal (Rogers et al., 2012). The stressful impact on foals when separated from their mothers, has been demonstrated using ABMs such as increased injuries and vocalisations (McGee & Smith, 2004). Separation stress is prevented if mares and foals are penned together.

3.2.5. Handling and moving to the stunning area

3.2.5.1. Description of handling and moving

Handling and moving refer to the process of moving horses from lairage to the stunning area. Werner and Gallo (2008) reported that plasma lactate concentration increased significantly when horses were moved from lairage to the stunning box, indicating stress.

In this respect, handled or unhandled horses are commonly moved differently:

• − Unhandled horses may be moved in a group to a holding or crowd pen and then moved through a passageway to the stunning area. After entering the stun box, they remain loose. In most of the cases, horses will enter the stun box individually. Unhandled horses might be distressed if separated from their group. Mares may become agitated and aggressive if handlers attempt to separate them from their foals.
• − Handled horses are usually removed one at a time from the holding pen (or directly from the lairage area) and led individually to the stunning box.

3.2.5.2. Highly relevant WCs identified for handling and moving

The highly relevant WCs occurring to horses during handling and moving were identified via EKE (see Section 2.2.3) and are presented in Table 7 with their definitions.

TABLE 7.

Highly relevant welfare consequences identified during handling and moving and their definitions.

Welfare consequence	Definition
Handling stress	See Section 3.2.3.2 (Table 5)
Injuries	See Section 3.2.2.2 (Table 4)
Restriction of movement	See Section 3.2.2.2 (Table 4)
Sensory overstimulation	See Section 3.2.3.2 (Table 5)
Separation stress	See Section 3.2.4.2 (Table 6)

A summary of information retrieved from literature complemented by expert opinion per each of these WCs is presented below.

Handling stress

Horses not used to the relevant handling (e.g. being led by a halter or moved in group in a passageway) might experience handling stress. Overall, the hazards occurring during unloading (see Section 3.2.3.2) are also present during handling and moving to the stunning area.

Horse behaviour shows individual variation and depends for example on their status as handled or unhandled, semi‐feral, breed, previous experience (Section 3.1.3) and temperament (Hausberger et al., 2008; Lloyd et al., 2008). This means that handlers will have to move and handle horses according to the reactions of individual animals and staff training plays a crucial role during handling and moving. Preventive measures include training handlers on species‐specific behaviour of horses, such as ear positions, vocalisations and tail swishing, to assist them in the suitable methods to handle and move horses in confined spaces. Unhandled and semi‐feral horses, being less accustomed to human interaction, will experience less handling stress if moved in small groups. Approaching a horse on the left side is also helpful to prevent handling stress, as horses are typically trained this way.

Injuries

Overall, the same hazards leading to injuries during lairage (see Section 3.2.4.2) and the same preventive measures apply during handling and moving.

Restriction of movement

The same hazards and preventive measures occurring during unloading (see Section 3.2.3.2) apply also during handling and moving. Additional hazards include narrow passageways, overcrowding in passageways with animals bunching together, inappropriate use of physical restraints such as halters held too tightly that can cause horses to pull back, and slippery or unsuitable flooring which can make horses fearful to move.

Unhandled horses are moved in a single line through a passageway. Horses used to being handled are usually led by the operator through a wide passage, with the handler next to the horse. Alternatively, the handled horses can be moved through a passageway with the operator outside the barrier leading the horse by halter and rope.

As prevention, the EU Best Practice at Killing (European Commission, 2017) states that passageways should be wide enough for animals to move in groups following their natural behaviour and without sharp turns. AVMA advises that the appropriate passageway width for horses is 32 inches (81 cm) and the width may need to be adjusted for exceptionally large or small animals (AVMA, 2016). Considering the average horse (intended as weighting 400kg, in this opinion), the EFSA experts consider that horses might experience restriction of movement when moved through passageways with a width below 80 cm.

Sensory overstimulation

Overall, the same hazards leading to sensory overstimulation during unloading (see Section 3.2.3.2) and preventive measures also apply during handling and moving.

Separation stress

When horses are moved individually from lairage to the stunning area one after the other they likely become anxious from separation from their pen mates (Zelazna & Jezieski, 2018).

As horses are herd animals (Boyd & Keiper, 2005), separation from their group can trigger stress even after a temporary separation (Mal et al., 1991; McDonnell, 2003; Newberry & Swanson, 2001; Zelazna & Jezieski, 2018). Stress induced by separation is potentially harmful to the horse's welfare as the horse become agitated (Keeling & Gonyou, 2001; Stroebe & Stroebe, 1987). An agitated horse left alone may be dangerous and injure himself and/or others.

Handled horses are typically used to be separated from their companions and temporarily isolated (Rybova et al., 2022), therefore they can be moved individually. If they show signs of separation stress, they should be moved with a companion animal.

Unhandled horses have generally been kept in a group and their first experience of separation may be at the slaughterhouse.

Unhandled animals, including youngsters (Knowles et al., 2010), will most likely display separation stress when moved individually, therefore handling these animals one at a time is not recommended. It has been shown that such animals moved with a conspecific were less agitated, required less encouragement to enter a stunning pen (20 m², intended for more than one animal at the same time) and experienced fewer slips and falls (Fletcher et al., 2023). In this study placing an excitable horse in the stun pen with a companion was effective in calming them both, with little or no reaction when the first horse was shot using a free bullet gun, followed rapidly by the shooting of the second animal. This paper reflects the particular situation where a stun pen is used.

The preventive measure is to move horses in pairs or in small groups in the passageways until they enter the stun box. This will limit agitation and motivate them to move forward as their herd‐mates do. Animals could be moved in pairs up to the stun box but not into the stun box. Animals might experience separation stress at the entry of the stun box, but moving them in pairs is still beneficial to prevent handling stress during handling and moving. If the horse in the stun box is stunned without any delay, separation stress is minimised.

The mitigation measure for a horse with signs of separation stress is additional care from the handlers, including consideration of the previous history of the animal to ensure separation stress is not exacerbated.

3.2.6. Restraint

3.2.6.1. Description of restraint

In this scientific opinion, restraint means applying to animals any practice designed to restrict their movements to facilitate effective stunning and bleeding. Individual horses may be restrained manually or mechanically (in a stun box) to present the head to the operator for the purpose of correct application of the stunning method. According to the European Commission (2017) horses require restraining before stunning with a penetrative captive bolt gun because the gun must be in contact with the head when firing.

The application of penetrative captive bolt in unrestrained horses will increase the risk of:

• − Injuries due to movements during fear response. Not being restrained will permit horses to move forward, backward and sideways, struggle, turn around etc. and increase the risk to slip, fall or hit structures. The risk will be particularly high in unhandled animals.
• − Pain due to failed loss of unconsciousness because of difficulties for the operator to shoot the bolt in the correct position and direction.

The use of firearms does not always require restraint, but in some cases, animals are restrained by a halter (see below).

Different methods are used for restraining horses before stunning. Types of restraint used for captive bolt stunning are stun boxes and halters/headcollars with a leading rope.

Stun box (Crush or narrow pen)

Horses can be confined in a stun box to gain easier access to their head. Stun boxes should be designed to allow horses to enter as willingly as possible with minimal stress (Driessen et al., 2022). The size of the stun box should not allow horses to turn around in the box and must therefore be adjusted to the size of the horse. This restraining method constitutes good practice, particularly for unhandled animals.

Floor conditions inside the stun box and the use of force by operators during the movement of horses into the stun box appeared to be crucial factors affecting both stunning effectiveness and stress through increased slipping (Fletcher et al., accepted for publication). Operators shouting, as opposed to speaking calmly or remaining quiet, resulted in more force required to move horses into the stun box and subsequently more slipping while animals were restrained (Fletcher et al., accepted for publication). Anti‐slippery flooring and regular cleaning will not only help to prevent restriction of movement and associated injuries but also improve the correct application of stunning methods.

Halter or headcollar or and lead rope

A halter with a lead rope can be used for handled horses. As a second choice, a head collar with a lead rope can be used to secure and restrict the movement of the head. All halters, head collars and other equipment used to restrain or handle horses should be fitted with a method of quick release in case a horse becomes entangled.

If a horse struggles or vocalises while being restrained, it often indicates that the restraint is causing discomfort. Active head restraint, where the head is clamped by a mechanised device should be avoided because these are more stressful for horses than full‐ body restrainers (AVMA, 2024).

Passive restraint, such as a tray to prevent the horse from lowering the head can be used.

3.2.6.2. Highly relevant WCs identified for restraint

The highly relevant WCs were identified via EKE (see Section 2.2.3) and are presented in Table 8 below.

TABLE 8.

Highly relevant WCs occurring to horses during lairage.

Welfare consequence	Definition
Injuries	See definition in Section 3.2.2.2 (Table 4)
Restriction of movement	See definition in Section 3.2.2.2 (Table 4)
Sensory overstimulation	See definition in Section 3.2.3.2 (Table 5)

A summary of information retrieved from literature complemented by expert opinion per each of these WCs is presented below.

Injuries

Injuries during restraint may result from an inappropriate restraint (i.e. too forceful or prolonged). If the operator uses excessive force to restrain the animal for the correct application of the stunning or killing method or if restraint lasts too long, the horse becomes agitated and the risk of injuries is increased.

Injuries may also result from collision with sharp edges, protrusions or slippery floors in the stun box, causing horses to slip and fall during restraint.

Preventive measures include training operators to restrain horses and understand the species and individual specific behaviour. If one person handles and restrains the horse, and another stuns the horse, there is a higher chance of shooting the animal before it becomes agitated (European Commission, 2017).

A non‐slip floor in the stun box is essential to prevent injuries due to slipping. Additional measures include a flat floor in the stun box, or a floor with a slight slope, avoiding steeply sloped or stepped floors and sharp edges or protrusions (AVMA, 2016).

Restriction of movement

Restriction of movement is inherent to restraint in the stun box. It will cause fear in most cases due to the inability of the animal to escape from a novel situation.

An inappropriate size of the stun box worsens the situation and is considered the main hazard. A too narrow stun box will hamper the entrance of horses, potentially leading to fear and panic response. A stun box that is too wide will allow horses to turn around, which will lead to extra handling and time in the box. This might also lead to injuries, especially in very small (ponies) or very large (e.g. draught horses) animals that are more prone to severe restriction of movements due to the inappropriate size of the stun box.

In the case of manual restraint of the head (without a stun box), a head collar and a lead rope, a halter or a bridle are used to secure and restrict the movement of the horse head. If the horse moves the head, the risk of failure of the stunning method is high (Fletcher et al., unpublished). Unhandled horses might be more reactive towards human proximity and might move more than handled animals.

The preventive measure is the use of mechanical restraint equipment designed for horses and adjusted to the size of the animal. In addition, starting the restraint only when the operator and the equipment are ready to proceed to stunning and killing can reduce the duration of restraint and shorten the associated restriction of movement. Related to head movements, more research is needed to find a suitable way to restrain horse heads to improve the effectiveness of stunning.

Restriction of movements and injuries are mitigated by calm handling when the horse is restrained, and the use of halters, head collars and other equipment adjusted to the animal size.

Sensory overstimulation

Fletcher et al. (unpublished) suggest that an important WC occurring during restraint can be the stress due to the inadequate design of the stun box. This occurs when a horse is loaded into a restraint originally designed for other species (such as cattle), as the horse, due to the relatively high head position of this species, often will be exposed to stimuli. These stimuli can be visual, auditory and olfactory involving a lot of movement, noise and novel odours, such as the shackling, hoisting and bleeding of previously stunned conspecifics. Indeed, Sabiniewicz et al. (2023) found that horses displayed clear behavioural reactions (e.g. ears back, greater vigilance) towards potentially threatening odours (tiger faeces and urine; horse blood) compared to socially attractive (opposite‐sex faeces and urine) and, in some cases, socially aversive (same‐sex faeces and urine) odours. Whether the sight of a dead conspecific being hoisted and dressed is stressful for the horse is not clearly established, but it is likely that the noise and movements linked with the processing of slaughtered horses will induce sensory overstimulation to the horse in the stunning box.

This situation is not unique to horses, but also applies to the slaughter of farmed deer in multi‐species slaughterhouses, a common practice in the UK, for which the Farm Animal Welfare Council (FAWC, 2003) recommended the use of specific restraining facilities.

As prevention, therefore, the EFSA experts suggest that the use of facilities specifically designed for horses can prevent sensory overstimulation. In particular, the sides of the stun box can be temporarily raised/lowered using extendable (or collapsible) wooden boards or curtains to facilitate operators to reach the head of horses of different height. Such an arrangement can prevent the horse restrained in the stun box from exposure to the visual, auditory and olfactory stimuli involved in the slaughtering process of previously stunned animals. Non‐slip wooden stairs or a step ladder adjacent to the stun box can help the operator reach the head of horses of different heights. It is also important to ensure such provisions do not interfere with the removal of effectively stunned animals from the stun box or prolong the stun‐to‐stick interval.

3.2.7. Animal‐based measures for all welfare consequences during Phase 1 (pre‐stunning)

The mandate requests to define animal‐based measures (ABMs) to monitor animal welfare during slaughter.

A feasible ABM during pre‐stunning should be minimally invasive for the animal, be collected quickly and with no (or only minimal) interference with normal operations, as also suggested for ABMs used to monitor animal welfare during transport (Llonch et al., 2015; Messori et al., 2016).

One limitation of ABMs during pre‐stunning, and specifically during arrival, is the limited possibility to see and access horses when they are in a vehicle.

For the pre‐stunning phase, some ABMs suggested in the EFSA horse transport opinion can be used (EFSA AHAW Panel, 2022b), in some cases after modifications inherent to the slaughter context.

It is to be noted that some WCs (e.g. restriction of movement) might be monitored through some ABMs during unloading (e.g. animal slipping and falling, wounds and sores) and through a limited number of ABMs during restraint (e.g. falling is not possible since the animal is restrained).

Furthermore, in some circumstances, no ABMs are available or feasible to use in the context of pre‐stunning of horses.

Tables 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 show the ABMs suggested per each WC, along with their description and an indication of the process for which they can be used.

TABLE 9.

ABMs for the assessment of gastro‐enteric disorders in horses (EFSA AHAW Panel, 2022b).

ABM	Description	Process
Diarrhoea	Faeces are discharged from the bowel frequently and in an abnormal form (e.g. liquid form). Gastro‐enteric disorders may alter the gastrointestinal absorption and motility leading to an increased volume and frequency of defecation, with faeces often not shaped properly.	Arrival
Colic clinical signs	Clinical signs of colic include changes in behaviour or activity that indicate abdominal pain. Horses may paw, roll, look at the belly, stop eating and drinking, urinate and defecate less, and assume abnormal posture during urination and defecation. Heart and respiratory rate and sweat score increase. A pain composite scale, including the behavioural and physiological parameters listed above, and a scale for facial signs of pain have been validated for colics.	Arrival

TABLE 10.

ABMs for the assessment of group stress in horses.

ABM	Description	Process
Aggressive behaviour towards conspecifics	Aggression is defined as threats or harmful actions directed towards another individual/animal and can include threat displays, rearing, kicking, pushing and biting (adapted from EFSA AHAW Panel, 2022b).	Lairage
Flat back ear position	Position of the ears is a possible behavioural indicator (body language) of the horse's behavioural response. For example, ears pricked forward indicate curiosity, ears flat back indicate fear or aggression (McDonnell, 2003)	Lairage

TABLE 11.

ABMs for the assessment of handling stress in horses.

ABM	Description	Process
Aggressive behaviour towards the handler	Aggression is defined as threats or harmful actions directed towards the handler and can include threat displays, rearing, kicking, pushing and biting (EFSA AHAW Panel, 2022b).	Unloading Handling and moving
Avoidance behaviour	Refusal to move forward and/or moving away from the source of an aversive situation (e.g. too much pressure applied by the handler, fear of the ramp) (EFSA AHAW Panel, 2022b)	Unloading Handling and moving
Snorting	Horses make noise with the nose, a forceful quick expiration from the nostrils. Snorting may indicate that horses are curious and examine unknown objects (Stomp et al., 2018). However, it can also be used to warn conspecifics that danger is present if loud and repeated.	Unloading Handling and moving
Flat back ear position	Position of the ears is a possible behavioural indicator (body language) of the horse's behavioural response. For example, ears pricked forward indicate curiosity, ears flat back indicate fear or aggression (McDonnell, 2003)	Unloading Handling and moving

TABLE 12.

ABMs for the assessment of heat stress in horses (EFSA AHAW Panel, 2022b).

ABM	Description	Process
Sweating (sweat score)	Evaporation of sweat is one of the mechanisms that horses use to lose heat and keep their core temperature in normal range. Sweating is a way of thermoregulating. The presence of sweat can be scored using the Sweat score (from 0 to 5), described by Holcomb et al. (2013), assessing the presence of sweat in five specific body regions: the neck, chest, girth, flank and hindquarters.	Arrival Unloading Lairage
Respiratory rate (RR)	Frequency of breathing, usually measured as the number of breaths per minute (bpm) (Mills et al., 2010). The normal range is between 8 and 12 bpm (Reed et al., 2017). Heat stress leads to an increased RR.	Arrival Unloading Lairage

TABLE 13.

ABMs for the assessment of injuries in horses.

ABM	Description	Process
Superficial skin lesions	Superficial tissue damage such as bruises and scratches, particularly on the tail, head, back and legs (EFSA AHAW Panel, 2012b; Mansmann & Woodie, 1995).	Arrival Unloading Handling and moving Restraint
Wounds and sores	Damage to the skin, muscle or bone tissue (adapted from EFSA AHAW Panel, 2022b).	Restraint Arrival Unloading Handling and moving

TABLE 14.

ABMs for the assessment of prolonged hunger in horses.

ABM

Body licking and chewing, stomach ulcers, latency to feed after unloading, body weight (EFSA AHAW Panel, 2022b)

Although in the horse transport opinion these ABMs were suggested for prolonged hunger, some of these are not considered feasible in the slaughter context (e.g. latency to feed after unloading, since animals are not usually fed before slaughter) or they are most likely more linked to farming conditions than to slaughterhouse conditions (e.g. stomach ulcers) and anyway no corrective action can take place at slaughter.

TABLE 15.

ABMs for the assessment of prolonged thirst in horses.

ABM	Description	Process
Abnormal drinking behaviour/Bucket test	Particular signs that horses are strongly motivated to drink include drinking for extended periods of time, gulping water, taking unusually long draughts or drinking until the trough is empty (Anon, 2014). A bucket test has been validated for horses (AWIN, 2015).	Arrival Lairage

TABLE 16.

ABMs for the assessment of respiratory disorders in horses (EFSA AHAW Panel, 2022b).

ABM	Description	Process
Nasal discharge	The horse presents discharge (serous, mucus, purulent) from its nostrils.	Arrival
Abnormal respiration	Dyspnoea (laboured breathing), tachypnoea (rapid breathing) and hyperpnoea (increased ventilation).	Arrival
Cough	Coughing is a vigorous inspiration, followed by a rapid exhalation, with the emission of a sound vibration.	Arrival

TABLE 17.

ABMs for the assessment of resting problems in horses (EFSA AHAW Panel, 2022b).

ABM	Description	Process
Resting behaviour	Time spent in tripodal standing, lateral or sternocostal lying.	Arrival

TABLE 18.

ABMs for the assessment of restriction of movement in horses.

ABM	Description	Process
Unable to walk comfortably/freely	The horse is unable to walk at its own pace, showing short steps, jumping or struggling (EFSA AHAW Panel, 2022b)	Arrival Unloading Lairage
Slipping and falling	Falling: Loss of balance in which parts of the body other than hooves and legs are in contact with the floor surface (adapted from cattle, Welfare Quality®, 2009). Slipping: Loss of balance in which the animal loses its foothold or the hooves slide on the floor surface. No other body parts except hooves and/or legs are in contact with the floor surface (adapted from cattle, Welfare Quality®, 2009).	Lairage Restraint
Loud vocalisations	Horses have a large range of auditory signals. Neighs and whinnies are loud, prolonged calls, typically of 1–3 s, beginning high‐pitched and ending lower‐pitched.	Restraint
Escape attempts	Attempts to go through or over gates and other barriers. Head and neck stretched forward and either held level with the back or slightly raised above or below the back line (extrapolated from cattle, from Lanier et al., 2001).	Restraint

TABLE 19.

ABMs for the assessment of sensory overstimulation in horses.

ABM	Description	Process
Alert behaviour	In the alert pose, horses mostly freeze, have their ears directed towards the stimulus and eyes wide open. This can be accompanied by a snorting noise from the nostrils meaning they are insecure or frightened. When this progresses to agitation or fear, the respiratory rate increases and they may sweat (EFSA AHAW Panel, 2022b).	Unloading Lairage Handling and moving Restraint
Avoidance behaviour	Refusal to move forward and/or moving away from the source of an aversive situation (e.g. too much pressure applied by the handler, fear of the ramp) (EFSA AHAW Panel, 2022b)	Unloading Lairage Handling and Moving Restraint
Sweating (sweat score)	Evaporation of sweat is one of the mechanisms to lose heat and keep the core temperature constant. Sweating is a way of thermoregulating (EFSA AHAW Panel, 2022b).	Unloading Lairage Handling and moving Restraint

3.3. Phase 2: Stunning

3.3.1. Introduction

Stunning is any intentionally applied method which causes loss of consciousness without causing avoidable pain or fear, including any methods resulting in instantaneous death.

In the context of stunning, the assessment of consciousness is the state that matters, because it is the prerequisite for experiencing any WC (e.g. injuries during neck cutting) and the underlying negative affective states, i.e. pain and fear.

Presence of a conscious animal after the application of a stunning method is due to either an ineffective stunning or the recovery of consciousness before death is induced by bleeding.

Therefore, in the stunning context, ABMs can be used to evaluate if animals are conscious and therein exposed to negative affective states such as pain and fear.

The main stunning methods employed in the slaughter of all categories of horses are mechanical (i.e. penetrative captive bolts and firearms). For each method, the WCs, ABMs, related hazards and preventive and corrective measures are described in Sections 3.3.2 and 3.3.3.

3.3.2. Penetrative captive bolt stunning

3.3.2.1. Description

Penetrative captive bolts powered by cartridge are commonly used to stun horses at slaughter. The guns are designed to fire a retractable steel bolt that penetrates the cranium and enters the brain. The impact of the bolt on the skull results in brain concussion and immediate loss of consciousness (EFSA, 2004). The penetration of the bolt into the skull and subsequent withdrawal cause structural damage to the brain due to cavitation, which results in marked subarachnoid and intraventricular haemorrhages, especially adjacent to the entry wound and at the base of the brain. The bolt diameter, speed and penetration depth are important parameters to ensure the efficacy of the stun. The penetration of the bolt causes subsequent disruption of brain tissue and prolongs the duration of unconsciousness and insensibility (EFSA, 2004).

Some guns have a captive bolt that protrudes from the muzzle when it is in the primed position, while others have a recessed bolt within the muzzle. Normally, when a bolt is fired, it requires a short distance to reach its maximum speed before impacting the skull. Therefore, at the time of firing, guns with protruding bolts should be kept at a short distance (up to 5 mm) from the animal's head, whereas guns with recessed bolts must always be pressed firmly against the head. Various factors, such as anatomical differences due to breed, sex or age of the animal, influence the efficacy of stunning.

Although death may occur, depending on the degree of injury to the brain (Lambooij & Algers, 2016), captive bolt stunning shall be followed as quickly as possible by bleeding or destruction of the brain and upper spinal cord by pithing.

3.3.2.2. Hazards for captive bolt stunning and prevention

An incorrect position of the shot (i.e. point of penetration in the skull) or direction may lead to ineffective stunning. For instance, Fletcher et al. (accepted for publication) observed horses slaughtered in an Italian abattoir during four non‐consecutive days and reported that 24% of horses (15/62), slaughtered, showed signs of ineffective stunning after being shot with a penetrating captive bolt and 10% were shot twice (6/62). Ineffective stunning was found to occur due to deviation from the correct shooting position recommended by HSA (HSA, 2016a, see below) (range of deviations = −60 to +80 mm sagittal and −55 to +65 mm lateral). In the same study, post‐mortem examination of the brains for macroscopic lesions in a subset of 43% (27/62) animals indicated that the majority (85%; 23/27) of effectively stunned horses showed some level of macroscopic damage to the thalamus, midbrain and brainstem structures. In contrast, in ineffectively stunned horses and those that required a second shot, the bolt had either missed the brain completely or inflicted mild damage to temporal or occipital lobes depending upon the extent of deviation from the ideal shooting position.

Another example of mis‐stunning due to incorrect position or direction is the study from Caraves and Gallo (2007), who evaluated the use of pneumatically operated (penetrating captive bolt 12 bar airline pressure; 1200 kPa) in 101 horses (frontal shooting position) in Chilean slaughterhouses and reported that 78.2% of the animals were effectively stunned by the first attempt and the rest needed two or more shots. Of the 101 horses stunned, 82% showed no sign of recovery of consciousness after the shot and during bleeding. When the location of the lesions on the skull was measured with respect to the correct shooting position, only 11.5% of the shots hit the target (within 2 cm). There was a low efficiency in the stunning process of horses, mostly due to inadequate shooting positions, that could be as far as 8 cm from the correct position. Inadequate shooting position can be due to lack of knowledge of staff and/or inefficient restraint (allowing horses to move their head at the moment of the shot).

Another hazard is the operator using a restraining technique that is not adequate to prevent movement of the animal, leading to a wrong application of the method (e.g. wrong shooting position, wrong direction etc.). In a recent study, Fletcher et al. (unpublished), reported that 28 out 100 horses showed behavioural signs of ineffective stunning in a commercial abattoir in Mexico. In all of them, the shot deviated more than 10 mm from the optimal position described by HSA (HSA, 2016). One possible reason is that horses, although restrained, may have moved the head leading to the wrong shooting position.

Incorrect captive bolt parameters (e.g. low cartridge power, low bolt speed, shallow penetration, too narrow bolt diameter and faulty equipment) (EFSA, 2004) are other hazards for ineffective stunning.

Fletcher et al. (accepted for publication) reported that under slaughterhouse conditions horses were shot with a captive bolt gun with 0.22‐inch diameter, 2.5 grains (purple) cartridges, quoted as delivering 238J (± 10%) of kinetic energy and recommended for use with small cattle, small pigs, ewes and goats. In this study, 24% (15/62) of the animals showed rhythmic breathing and other signs of consciousness after the first shot. The rates of ineffective stunning were most probably due to the underpowered cartridge, recommended for use on small animals and not on horses.

To prevent failure, according to the Humane Slaughter Association (HSA), the optimal site for captive bolt stunning is in the middle of the forehead (Figure 2) and about 1 cm above the intersection point of a diagonal line from the centre of the eye to the centre of the base of the opposite ear (HSA, 2016a).

FIGURE 2.

Correct shooting position for captive bolt stunning of horses (© HSA, Humane Slaughter Association): The correct point of entry of the projectile is at 1 cm above the intersection of two imaginary lines, each drawn from the centre of the eye to the centre of the base of the opposite ear.

The correct direction of the bolt is when it targets the brain stem (AVMA, 2016) (Figure 3).

FIGURE 3.

Direction of the shot (© AVMA, American Veterinary Medical Association).

The HSA (HSA, 2016a) recommended to use the types of cartridges suggested by the manufacturer for the equipment and type of animal (e.g. foal vs. stallion).

Cartridges vary in strength and are classified according to the amount of propellant (gun powder) they contain, with 3.0 grains and 4.0 grains suggested for larger horses such as draught horses (1 grain = 0.0648 g).

The speed and penetration depth of captive bolts are determined by the captive bolt gun performance. The minimum recommended bolt speed (European Commission, 2017) is 55–70 m/s, with a minimum bolt diameter of 9 mm and a recommended penetration depth of at least 7 cm. The EFSA experts consider that these parameters lead to an effective stunning of horses, assuming that other factors, such as position and direction of the shot, are applied correctly. However, there is no published data to suggest that these parameters are valid for all horse categories. Furthermore, studies in cattle indicated that even when the recommended captive bolt parameters were applied, not 100% of the cattle were effectively stunned due to reasons related with the thickness of skull (in addition to movement of the animals and lack of skill of the staff) (Atkinson et al., 2013).

Staff training and rotation, use of an appropriate restraint, proper placement and firing of the gun, the use of equipment that is fit for the purpose, and regular cleaning and maintenance of the equipment according to the manufacturer's instructions (also see HSA, 2016a) are preventive measures. Routine checking and maintenance of captive bolt guns, particularly when repeat firing occurs in a session, can prevent carbon build‐up and ensure optimal performance.

After an ineffective shot, the corrective measures are to re‐stun as soon as possible in the correct position, in the correct direction and with the proper captive bolt parameters or re‐stun with a backup method.

When a captive bolt enters the skull, it causes massive damage to the brain and acute swelling around the skull wound. This means that, in case of a second shot, the swelling will absorb much of the impact and therefore the second shock wave will not be effectively transmitted to the brain. As a corrective measure, the repeat position must always avoid the immediate area of the first shot. If the first shot is off target, the second should be placed as close to the correct stunning position as possible. If the first shot is on target, but fails to produce an effective stun, the second shot should be above and to one side. If a third shot is required, this should be above and to the other side of the first shot (HSA, 2016a).

In general, training staff to acquire knowledge and understanding of signs of ineffective stunning and take appropriate measures to mitigate poor welfare outcomes is crucial.

3.3.2.3. Animal‐based measures (ABMs) to monitor effectiveness of ‘Captive bolt stunning’

In the stunning context, ABMs are the indicators assessed to evaluate if animals are conscious and therefore exposed to negative affective states such as pain and fear.

According to the EC factsheet (EC, 2017), signs of unconsciousness after effective captive bolt stunning are immediate collapse, apnoea, tonic–clonic seizures, absence of eye reflexes (palpebral and corneal), fixed eyes with glazed expression and lack of response to painful stimuli (pinch or prick of the nose or ear). Figure 4 shows these signs and their anatomical localisation.

FIGURE 4.

Signs of unconsciousness in horses stunned with a penetrative captive bolt (© EC, European Commission).

In line with other scientific opinions on the slaughter of various animal species (e.g. EFSA AHAW Panel, 2013), it is important to assess the overall state of consciousness of the animal, which includes an assessment of both signs of consciousness and unconsciousness. If signs of consciousness appear after stunning, an appropriate backup stunning method applied immediately can mitigate the WCs.

Werner and Gallo (2008) found that after captive bolt stunning, 57% (out of the 21 horses studied in one Chilean slaughterhouse) showed signs of returning to consciousness during exsanguination, with a most frequent stun‐to‐stick interval of 1–2 min. The main signs of return to consciousness observed were rhythmic breathing, corneal reflex, ocular movement, head elevation, vocalisation and attempts to regain posture.

In Fletcher et al. (accepted for publication), 15 of the 62 animals (24%) showed signs of ineffective stunning. Three animals failed to collapse, and two animals attempted to get up after collapsing. All 15 animals showed rhythmic breathing, 2 had corneal and palpebral reflexes, others showed eyeball rotation (5) and nystagmus (6).

Based on these studies and the extrapolation of indicators from cattle (EFSA AHAW Panel, 2013), the EFSA experts suggest the flowchart in Figure 5 to monitor the effectiveness of penetrative captive bolt stunning of horses.

In the flowchart, ABMs to monitor the state of consciousness are suggested and included in toolboxes (blue boxes), to be used at three key stages ((1) Between the end of stunning and shackling, (2) During neck cutting or sticking, (3) During bleeding). For each key stage, three or four ABMs that are reliable for monitoring consciousness are suggested (above the dashed line), plus two or three other ABMs, which are less reliable, that can be additionally used (below the dashed line). For each ABM, the corresponding signs of consciousness and unconsciousness are reported (EFSA AHAW Panel, 2013). In case outcomes of consciousness are observed at key stage 1, an intervention should be applied (i.e. repeat the stunning in an appropriate way, such as adjusting the position or direction, or re‐stun with a backup method). After any re‐intervention, the monitoring of unconsciousness should be performed again. The process can continue to the next step only when signs of unconsciousness are observed. After key stage 3, only when signs of death are observed (see Section 3.4.3), the process can be continued (i.e. dressing of the carcass).

3.3.3. Firearm with free projectile

3.3.3.1. Description

Firearms with free projectile, such as shotguns and rifles, can be used to kill horses. This is a one‐step stunning and killing method and does not necessarily require restraint. After a successful head shot, death is immediate.

The HSA (HSA, 2016b) lists several firearms that are useful for slaughter of horses, including shotguns (12, 16, 20, 28 and .410 gauges), handguns (.32 to .45 calibre) and rifles (.22, .243, .270 and .308). In general, when comparing handguns with rifles, the longer the barrel, the higher the muzzle speed. Therefore, if a .22 is used for slaughter, it is best fired from a rifle (AVMA, 2016). In slaughterhouses, animals are shot at a close distance (i.e. maximum 3 m) and the requirement is that the bullet possesses sufficient energy to penetrate the skull and enter the underlying brain tissue. The impact of the bullet on the skull will send shock waves through the brain and tumbles while travelling through the brain creating cavitation and severe structural damage. To improve energy transfer upon impact and prevent exiting the target tissue, bullets are constructed to fragments and/or deform after hitting the target (known as Dum Dum bullets). Deformation projectiles do not lose any material, so that the projectile in the target tissue weighs almost as much as the original projectile. This type is mainly used in handguns and possess muzzle speeds below 450 m/s. In the case of fragmentation projectiles, the loss of mass accounts for up to half of the original mass.

Millar and Mills (2000) evaluated a .32 free bullet pistol (5.51 g; n = 12 horses) and found variation in the degree of intracranial damage by assessing the gross pathology of the brain but did not assess the effectiveness in provoking immediate death or recovery of consciousness. Another study carried out in Brazil (n = 4 horses and 4 mules), involving a .22 calibre rifle and warhead projectile, reported that five animals had to be shot two or more times before being rendered unconscious (Machado et al., 2013). In contrast, a study in an English slaughterhouse reported no animals (n = 46 horses) showing signs of consciousness following one shot with a free bullet rifle (Gibson et al., 2014). The sample size, firearm/ammunition characteristics, operator competence, animal type and level of restraint may explain the differences in results (Gibson et al., 2014).

Gibson et al. (2014) evaluated the effect of shooting horses and ponies with a .22 long rifle (copper plate hollow point (≈ 2.6 g) 40 grains, rounds). The results clearly showed that all the animals (n = 46) were rendered immediately unconscious, with only one pony showing signs of a shallow depth of concussion, having an intermittently positive palpebral reflex but no other signs of brainstem function. All animals had some degree of damage to the structures of the brainstem or lobes of the cerebrum, while 41 (89%) had damage to the thalamus/hypothalamus. In one pony, the bullet missed the brain but still caused mild damage to the thalamus, midbrain, pons and cerebellum, and this animal showed no signs of consciousness. The findings confirm that free bullet shooting is an effective method of killing horses and ponies when using the correct shooting position and the appropriate parameters.

3.3.3.2. Hazards for firearms and prevention

An incorrect position of the shot, due to lack of skilled operators, operator fatigue, wrong target area or angle of shooting, can lead to ineffective stunning. The correct position has been described by HSA (2016b) as being 2 cm above the crossing of 2 imaginary lines going from the centre of an eye to centre of the opposite ear, with the muzzle of the firearm slightly tilted so that the shot is directed through the cerebral cortex towards the brain stem. The EFSA experts consider this shooting position comparable to the one recommended for captive bolt stunning (i.e. 1 cm above the intersection of the two imaginary lines described) and therefore suggest the latter also for firearms.

Sudden movements of the head of the horse could lead to the projectile failing to enter the skull or missing vital parts of the brain.

Ineffective stunning may also occur due to an inappropriate power and calibre of the cartridge, delivering insufficient energy to damage the brain depending on the breed, age, sex and live weight of the horse.

Similarly, the type of projectile might be inappropriate to the type of animal and the shooting distance. Metal‐sleeved or jacketed high‐speed bullets may exit the skull without sufficiently damaging the brain.

Stefanie et al. (2014), in a study on cattle, reported that the type of projectile, i.e. deformation or fragmenting bullet, did not have any effect on the effectiveness of destruction of the brain. However, the advantage of using soft point bullets compared to full metal jackets is that they expand when they hit the target and release more energy into the tissue. This is important to cause sufficient destruction of the brain.

As prevention, the use of appropriate firearms and ammunitions is essential. Staff training can help prevent the incorrect shot position and the choice of inappropriate power, calibre of the cartridge and type of projectile. It is also important to follow the manufacturer's instructions. Training the staff to use adequate practices to monitor (un)consciousness will prevent and correct shooting failures. Finally, inadequate shooting should be corrected by application of a second shot after correction (e.g. correcting position, direction or bolt parameters).

3.3.3.3. Animal‐based measures (ABMs) to monitor the effectiveness of ‘Firearm with free projectile’

The same signs of consciousness suggested for penetrative captive bolt stunning also apply to firearms with free projectiles (see flowchart in Figure 5).

3.4. Phase 3: Bleeding

3.4.1. Introduction

Exsanguination of horses immediately after stunning is an important step in the slaughter procedure, intended to cause death in unconscious animals.

In commercial slaughterhouses, after captive bolt stunning, which is the most used method, the unconscious animal is shackled and hoisted and moved via an overhead rail to the bleeding area. Horses are then bled out with a chest stick (referred to as sticking) or by neck cutting.

Chest sticking is aimed at severing the brachiocephalic trunk, which gives rise to the carotid arteries by supplying oxygenated blood to the brain (HSA, 2016a). Chest sticking is performed by inserting a knife in the ventral part of the base of the neck, just in front of the sternum, towards the thoracic inlet.

In other species, such as cattle, the formation of a false aneurism after severance of the carotids may lead to slowing down or stopping the bleeding, while vertebral arteries can still supply blood to the brain, with the risk of recovery of consciousness.

Although the literature suggests that vertebral arteries do not supply blood to the brain of horses (Levine et al., 2008), there is no published information on the incidence of false aneurisms following the severance of carotid arteries in horses.

Monitoring the effectiveness of the killing (i.e. confirmation of death) is required for every horse killed, before dressing the carcasses, to avoid dressing animals alive.

3.4.2. Hazards for ‘Bleeding following stunning’ and prevention

Prolonged stun‐to‐stick interval is a hazard that occurs when the interval between the time of stunning and of sticking is too long to guarantee unconsciousness until death due to bleeding.

Sticking (incision of the skin, soft tissues, nerves and brachiocephalic trunk) of conscious horses is a hazard that applies to ineffectively stunned horses or those recovering consciousness before sticking. Lack of skilled operators and lack of monitoring consciousness at the time of sticking are hazard origins.

Owing to the number of operations, there is an inevitable delay between the time of stunning and the time of sticking. Lack of a skilled operator, delayed shackling as well as hoisting and sticking of animals (e.g. when stunned animals convulse excessively or when it is difficult to eject the animal from the stunning box because of the collapsed position) and bleeding rail far from the stunner are therefore the causes of this hazard.

There is no published scientific information to provide a maximal stun‐to‐stick interval in horses.

European Commission (2017) recommends a stun‐to‐stick interval of 15 s, but it is doubtful whether this can be achieved under commercial slaughterhouse conditions, as the effectively stunned horses will have to be rolled out of the stun box, shackled and hoisted before proceeding to chest sticking or neck cutting.

Under commercial slaughter conditions, the stun‐to‐stick interval ranges between 40 and 60 s (European Commission, 2017); however, Fletcher et al. (accepted for publication) reported a mean stun‐to‐stick of 71 s (SD 15.1 s; min‐max = 34–130 s).

A maximum stun‐to‐stick interval of 60 s after penetrative captive bolt stunning has been suggested by HSA (HSA, 2016a).

In a study (Werner & Gallo, 2008), the stun‐to‐stick interval was more than 1 min in 95% of the cases (due to low level of coordination between the staff performing stunning and the staff performing bleeding) and in some cases it was up to 4 or 5 min. Such long stun‐to‐stick interval was associated with 57% of animals (out of 21 horses) showing signs of consciousness return during bleeding.

Considering the absence of data, the stun‐to‐stick interval of 60 s recommended by EFSA for cattle can be considered as the maximum stun‐to‐stick interval also for horses. This is only a guidance and ABMs of consciousness (see Figure 5) have to be checked before and during bleeding. When there is any ABM indicating consciousness, the animal should be re‐stunned immediately.

The preventive measure is to ensure the bleeding post is empty before stunning a horse, and then swiftly shackle and hoist the horse, when ejected from the stun box. Overall, the appropriate stun‐to‐stick interval needs to be calculated considering the prevailing stunning method and slaughter conditions.

The use of blunt or short knives for exsanguination is another hazard for bleeding, leading to the incomplete sectioning of the brachiocephalic trunk or of the carotid arteries resulting in oxygenated blood supplied to the brain, which ultimately leads to recovery of consciousness in effectively stunned horses and prolongs the time to onset of death.

The preventive measure is to use a pointed and very sharp knife with a rigid blade (Woods & Shearer, 2015) that severs the jugular veins and carotid arteries. In addition, a chest stick can be performed to optimise bleeding. When properly performed and the sticking wound is large enough, the blood flows freely (Woods & Shearer, 2015).

Finally, if horses recover consciousness while undergoing dressing following sticking, the animals will experience severe pain and fear.

Corrective measures include the use of a backup stunning method when animals show signs of consciousness and cutting again properly the brachiocephalic trunk if bleeding is slow in unconscious animals.

3.4.3. ABMs in the context of ‘Bleeding following stunning’

In the interval from stunning to death, it is essential to monitor signs of consciousness constantly to avoid bleeding a conscious animal (see Flowchart in Figure 5).

In addition, it is also essential to confirm death before dressing. Signs of death have been extrapolated from cattle (EFSA AHAW Panel, 2013) and are the following: relaxed body (complete and irreversible loss of muscle tone, which can be recognised from the limp carcass), cessation of bleeding from the sticking wound and dilated pupils.

3.5. Emergency slaughter

In general, emergency slaughter means slaughtering animals due to unforeseen circumstances that necessitate immediate action, e.g. animals that are injured or have a condition associated with severe pain, and there is no other practical possibility to alleviate this pain. Typically, animals that cannot be moved without causing additional suffering are killed on the spot.

Horses showing signs of severe restriction of movement (e.g. severe lameness, bone fractures, joint dislocations and open wounds) or fatigue may arrive at the slaughterhouse and emergency slaughter should be carried out whilst the animal is still on the transport vehicle. It is important to prevent other animals from trampling on the recumbent or immobile animal, and therefore emergency slaughter may have to be performed after unloading the other animals.

Similarly, animals may develop signs of severe restriction of movement and fatigue in lairage, and they may have to be slaughtered during the lairage period.

The Farm Animal Welfare Council (2003) recommended that the slaughterhouse operators ensure that methods for emergency slaughter are clearly displayed at the unloading site, so that any animal in obvious pain or distress upon arrival at the slaughterhouse can be slaughtered immediately.

3.6. Unacceptable methods or practices on welfare grounds

The mandate requests to identify methods that are unacceptable on welfare grounds. In response to this ToR, the EFSA experts listed practices and classified them as leading to severe pain and fear, based on expert opinion. However, due to lack of information, the severity of pain and fear associated to these practices is unknown. These practices are considered unacceptable on welfare grounds and should be avoided.

Firstly, the EFSA experts agree with Council Regulation (EC) 1099/2009 on unacceptable methods and practices and the list of restraining methods that are prohibited. Some of these methods can be related to the slaughter of horses:

• ○ suspending or hoisting conscious animals;
• ○ mechanical clamping or tying of the legs or feet of animals;
• ○ severing the spinal cord, such as using a puntilla or dagger;
• ○ use of electric currents to immobilise the animal that do not stun or kill it under controlled circumstances, and, in particular, any electric current application that does not span the brain.

Similarly, the EFSA experts agree with the principle in Chapter 7.5.10 of the WOAH Terrestrial code (OIE, 2019), which says that ‘methods and practices e.g. restraining methods […] that cause severe pain and stress in animals, cannot be considered acceptable’. For example, the EFSA experts consider unacceptable from the welfare perspective the following practices:

• ○ moving severely injured horses or those unable to move independently;
• ○ use of painful procedures to move horses (e.g. electric goads, sticks) or restrain them (e.g. twitches);
• ○ sticking and bleeding of conscious horses.

3.7. Specific hazards related to types of animals

Some horse types are at a higher risk of experiencing WCs. Most of these were presented in different sections of this opinion, along with specific preventive measures:

• − unhandled and semi‐feral horses are more prone to handling stress than handled horses (see Section 3.2.5.2 under handling stress);
• − horses with specific temperament (e.g. due to previous conditions of housing, management and handling, specific breeds) are more prone to fear (Lloyd et al., 2008); (Section 3.2.5.2 under handling stress);
• − very small (ponies) or very large (e.g. draught horses) animals might not fit in the stun box and are more prone to severe restriction of movements and injuries during restraint (see Section 3.2.6.2 under restriction of movements);
• − stallions are prone to fight with other individuals (especially other stallions and geldings) and represent a high risk of group stress and injuries (see Section 3.2.4.2 under group stress);
• − mares may panic when separated from their foal and this will lead to separation stress (see Section 3.2.4.2 under separation stress);

In addition, lactating mares can experience discomfort due to udder engorgement and intramammary pressure. Prioritisation of these mares in the slaughter order can mitigate this.

Other animals that risk poor welfare at slaughter are pregnant mares and their fetus. This issue was addressed in a previous EFSA opinion on the slaughtering of pregnant animals (EFSA AHAW Panel, 2017) and a summary is reported here.

Based on the available scientific evidence, it cannot be determined with certainty whether livestock fetus are capable of conscious perception. Using the available scientific literature and expert opinion, EFSA (EFSA AHAW Panel, 2017) concluded on the capacity of livestock fetus to experience pain and other negative affect using an approximate probability scale. In short, the respective outcomes are:

1. It is very likely to almost certain (i.e. a 90%–100% likelihood derived from EKE) that animal fetus in the last third of gestation have the anatomical and neurophysiological structures/correlates for experiencing pain and/or other forms of discomfort.

2. Regarding the possibility that fetus perceive negative affect, there are two different possibilities for which EFSA expressed two different likelihoods: (a) it is more probable that the neurophysiological situation does not allow for conscious perception (66%–99% likelihood) because of brain inhibitory mechanisms; (b) there is a lower probability that livestock fetus can experience negative affect (1%–33% likelihood) arising from differences in the interpretation of the fetal electroencephalogram, observed responses to external stimuli and the possibility of fetal learning.

3. Since all slaughtering practices involve a maternal circulatory collapse and rapid fetal hypoxia, it is extremely unlikely to unlikely (1%–33% likelihood) that changes/responses occurring during stunning and bleeding of the dam are associated with pain or other negative affect in the livestock fetus.

Therefore, irrespective of the stunning method used, the most relevant hazard for fetus in the last third of gestation is the killing of the dam during the slaughter procedure. A set of scenarios and respective preventive or corrective actions for both the assumptions that livestock fetus might or might not perceive pain or other negative affect (see point number 2 in the previous paragraph) is provided in Figure 6.

FIGURE 6.

Scenarios and respective courses of action as regards handling of the fetus/neonate under different assumptions regarding the neurophysiological situation of the fetus (modified after EFSA AHAW Panel, 2017).

3.8. Results of uncertainty analysis

Table 20 shows the key conclusions with potential relevance for risk management. For each conclusion, the table provides the questions to express certainty. For each question, the population is (hypothetically) exposed to the scenario described in the conclusion and the proportion of the population affected by the relevant WC judged against a reference quantity (rQ) (see Section 2.2.5 for details). The selection of the rQ considered the perceived impact of a specific WC on the animals and varies depending on the WC considered.

TABLE 20.

Conclusions, questions and results of the uncertainty analysis for the key conclusions.

Conclusion	Question for uncertainty assessment	Certainty range
In the lairage area, high effective temperature (exceeding the upper critical temperature of 25°C) and inadequate ventilation lead to heat stress.	How certain are you that > 20% of horses will experience heat stress when the T° in lairage is exceeding 25°C?	66%–100% Reason for this certainty range is that factors such as duration of exposure and humidity have an impact on heat stress but they cannot be easily taken into account.
Regarding horizontal space, for horses lairaged in collective pens, a stocking density exceeding 110 kg/m2 leads to resting problems.	How certain are you that > 20% of horses lairaged at a stocking density of more than 110 kg/m2 will experience resting problems?	66%–100% Reason for this certainty range is the large variation in horse size. While many horses might experience resting problems with this stocking density (e.g. not being able to reach the drinker, or rest all together at the same time etc.), others may not. Extremely large animals will certainly experience resting problems, however they are a minority of the total horses slaughtered.
Narrow passageways (i.e. < 80 cm) lead to restriction of movements.	How certain are you that > 20% of horses being moved from lairage to the stunning area will experience restriction of movements if passageways have a width of less than 80 cm?	66%–100% Reason for this certainty range is the large variation in horse size. For instance, ponies might pass through a passageway less than 80 cm wide but the average size animals and extremely large animals will struggle or not pass through it. In addition, also the variation in previous experience of the horse in passing in narrow passageways will influence the likelihood of the WC.
In lairage, a vertical space of less than 2.7 m (floor‐to‐ceiling height) leads to restriction of movements when raising the head and rearing, especially during interaction with other animals.	How certain are you that > 20% of horses being kept in lairage with a vertical space of less than 2.7 m (floor‐to‐ceiling height) do experience restriction of movements while raising the head and rearing during interactions?	90%–100% The remaining uncertainty relates to the lack of information on the requirements of animals in lairage and the variation in size. However, below this height most horses will not be able to raise the head and rear.
Before weaning, mares and their foals are distressed from being separated in different pens in lairage.	How certain are you that > 20% of mares and their foals do experience separation stress if separated in different pens?	90%–100% There is almost no uncertainty, this conclusion corresponds to the narrower range 99%–100% (almost certain).
Stallions housed in groups are prone to fight with other individuals.	How certain are you that > 20% of stallions do experience group stress (i.e. aggressive interactions) if housed in groups together?	90%–100% There is almost no uncertainty, this conclusion corresponds to the narrower range 99%–100% (almost certain).
Pen fences that are not made of solid partitions from the floor for at least a meter increase the likelihood of horses getting injured (e.g. trapping their feet).	How certain are you that > 20% of horses kicking or pawing through the fence without solid partitions of at least one meter in the sides will get injured due to trapping their feet?	90%–100% The remaining uncertainty related to the fact that the chance of feet trapping is very high if no solid partition for at least 1 m is provided, but there is no data about the proportion of horses that perform behaviours like kicking and risk getting trapped.
Using adequate captive bolt parameters (minimum bolt diameter of 9 mm, minimum bolt length of 8 cm and speed of at least 55 m/s) leads to effective stunning when all other factors dependent on the technique (such as position and direction of the shot) are applied correctly.	How certain are you that 99% or more of horses stunned with captive bolts with a minimum bolt diameter of 9 mm, a bolt length of 8 cm and a speed of at least 55 m/s are unconscious (assuming stunning is applied correctly)?	66%–100% There is uncertainty because these parameters are not validated and other factors not related to the technique but related to the animal (e.g. conformation and thickness of the skull) may influence the effectiveness of the technique.
The correct shooting position for captive bolt stunning is about 1 cm above the intersection point of a diagonal line from the centre of an eye to the centre of the base of the opposite ear, with the bolt targeting the brain stem.	How certain are you that 99% or more of horses that have been stunned with captive bolts with a shooting position of 1 cm above the intersection point of a diagonal line from the centre of an eye to the centre of the base of the opposite ear are unconscious (assuming other parameters are applied correctly, e.g. bolt power, bullet speed and size etc.)?	66%–100% There is uncertainty because animals might be ineffectively stunned even though the shooting position was correct due to other factors linked to animal anatomical variability (e.g. conformation and thickness of the skull).
The correct shooting position for firearms is 1 cm above the intersection point of a diagonal line from the centre of an eye to the centre of the base of the opposite ear, with the bolt targeting the brain stem.	How certain are you that 99% or more of horses that have been stunned with firearms with a shooting position of 1 cm above the intersection point of a diagonal line from the centre of an eye to the centre of the base of the opposite ear are unconscious (assuming other parameters are applied correctly, e.g. bolt power, bullet speed and size etc.)?	90%–100% Despite some uncertainty linked to animal anatomical variety (e.g. conformation and thickness of the skull), shooting with firearms has a very high likelihood of destroying the brain even when the shooting position is slightly deviated.
A maximum stun‐to‐stick interval of 60 s prevents recovery of consciousness during bleeding.	How certain are you that 99% or more of horses stuck (neck cut) within 60 s after effective stunning will not recover consciousness before death?	66%–100% This uncertainty is because this interval is extrapolated from recommendations on cattle and there is no data on horses.

For each question, experts were asked to provide their individual judgements together with the rationale. A consensus range reflecting the collective certainty about the statement was reached through group discussion or, if consensus could not be achieved, the wider range encompassing all individual judgements was retained.

In the uncertainty assessment of key conclusions on correct stunning, an additional source of uncertainty was identified that could not be quantified due to lack of information. The uncertainty refers to the situation where a horse might move the head during stunning because of lack of proper handling by the operator and/or lack of proper restraint specifically designed for horses.

For conclusions related to arrival and unloading, the uncertainty assessment was not performed as they are reported from the EFSA transport opinion.

4. CONCLUSIONS

Preamble: conclusions and recommendations related to the arrival and unloading processes have been compiled in a previous EFSA opinion on transport of Equidae (EFSA AHAW Panel, 2022b); those that are relevant to the slaughter context are reported here. Certainty assessments are provided in brackets below only for key conclusions that could be considered for risk management decisions.

4.1. Conclusions for arrival

1. The highly relevant WCs that horses might experience at arrival are: gastro‐enteric disorders, heat stress, injuries, prolonged hunger, prolonged thirst, respiratory disorders, resting problems, restriction of movement and sensory overstimulation.

2. At arrival, a temperature above 25°C inside the vehicle might lead to heat stress. This will vary depending on factors such as the humidity in the vehicle, the duration of exposure, the individual horse, the breed and the degree of acclimatation to heat.

3. At arrival, injuries due to transport are the results of the following hazards: lack of bedding in the vehicle, slippery floor, unsuitable vehicle, orientation towards the road inside the vehicle, lack of space, lack of training of the horse and/or of the handler, mixing of unfamiliar horses.

4. At arrival, horses might experience prolonged hunger and prolonged thirst. Hunger may occur after approximately 12 h since last meal, while thirst may start after just 3 h of water deprivation.

5. Respiratory disorders can result from restrictive tying practices in the vehicle.

6. Resting problems at arrival occur when horses cannot adopt one of their physiological resting positions (i.e. tripodal or lying down) during transport.

7. For horses transported in individual stalls, a free space of at least 40 cm in addition to the horse's maximum width and of at least 40 cm in addition to the body length measured from the tail to the nose while the neck is kept horizontally prevents restriction of movements.

8. For horses transported in groups, restriction of movement is a consequence of the space allowance or stocking density during transport. The limited available evidence (implying significant uncertainty) suggests that a stocking density of less than 200 kg/m² leads to improved welfare compared to higher stocking densities.

9. A minimum in‐vehicle vertical space of 75 cm from the height of the withers of the tallest animal prevents restriction of movement. However, the lack of evidence‐based thresholds constitutes a gap in knowledge.

4.2. Conclusions for unloading

1. During unloading, horses might experience the following WCs: handling stress, heat stress, injuries, restriction of movement and sensory overstimulation.

2. Several hazards may lead to injuries, handling stress and restriction of movement during unloading: the horse's level of training, transport‐related behavioural problems, unsuitable vehicles and facilities (i.e. ramp) and inappropriate handling by the operators.

3. The presence of unfamiliar auditory, visual and/or olfactory stimuli during unloading may lead to sensory overstimulation.

4.3. Conclusions for lairage

1. At lairage, the highly relevant WCs are group stress, heat stress, injuries, prolonged hunger, prolonged thirst, sensory overstimulation, resting problems, restriction of movement and separation stress.

2. When housed in a group, conflict with pen mates (especially unfamiliar animals) and inadequate resource allocation increase the risk of group stress and injuries. Particularly, stallions are prone to fight with other individuals (certainty 90%–100% ‐ very likely).

3. Unweaned foals and mares are distressed from being separated in different pens (certainty 90%–100% – very likely).

4. Injuries mainly result from improper design, improper construction and maintenance of lairage facilities, and broken structures (e.g. gates) and metal parts.

5. In the lairage area, a high temperature (i.e. > 25°C) might lead to heat stress. This varies depending on the humidity, the duration of exposure, the individual horse conditions, the breed and the degree of acclimatisation to heat, implying high uncertainty (certainty 66%–100% – likely).

6. At the entry in lairage, animals still experience the hunger and thirst that they were experiencing upon arrival. Hunger will persist till the horse is slaughtered as usually no feed is provided in lairage (unless it is known that the animals have spent more than 12 h from their arrival at the slaughterhouse), while thirst can be corrected by provision of water.

7. Lack of water provision or inappropriate design or construction of the drinking point preventing horses from easily accessing clean water at all times can result in prolonged thirst and dehydration.

8. Regarding horizontal space, for horses lairaged in collective pens, a stocking density exceeding 110 Kg/m² leads to resting problems (certainty 66%–100% – likely).

9. Regarding horizontal space, for horses lairaged in individual stalls, a stall providing less than 40 cm in addition to the horse's maximum width and 40 cm in addition to the body length will lead to resting problems.

10. In lairage, a vertical space of less than 2.7 m (floor‐to‐ceiling height) leads to restriction of movements (for an average horse) when raising the head and rearing, especially during interaction with other horses (certainty 90%–100% – very likely).

11. Lairage pen fences which are not high enough (i.e. above the withers) lead to an increased risk of horses escaping and getting injured. Furthermore, pen fences not made of solid partitions from the floor for at least one meter increase the likelihood of horses getting injured (e.g. trapping their feet) (certainty 90%–100% – very likely).

12. For animals housed individually, lairage pen fences that do not allow visual contact with other horses may lead to separation stress.

13. A lairage floor that is dirty, wet and slippery leads to increased risk of injuries and restriction of movement. In addition, a drainage system positioned across the pen might (rather than along the walls) also lead to injuries.

14. The presence of unfamiliar auditory, visual and/or olfactory stimuli during unloading may lead to sensory overstimulation.

4.4. Conclusions for handling and moving

1. During handling and moving horses to the stunning area, the highly relevant welfare consequences include handling stress, injuries, restriction of movement, sensory overstimulation and separation stress.

2. The same hazards leading to handling stress, restriction of movement and sensory overstimulation during unloading also apply during handling and moving animals to the stunning area.

3. Restriction of movement results from narrow passageways, i.e. < 80 cm overcrowding in holding pens or passageways leading to animals bunching together, inappropriate use of physical restraint such as tightly held halters causing horses to pull back, and slippery or unsuitable floor covering (certainty 90%–100% ‐ very likely).

4. Horses may experience separation stress when moved individually from lairage to the stunning area, due to separation from their pen mates.

5. Unhandled horses and semi‐feral are more at risk of handling stress than handled horses.

6. Mares and foals experience separation stress if moved separately from their foals.

4.5. Conclusions for restraint

1. The effective application of the penetrative captive bolt stunning method requires restraint whereas firearms do not require restraint.

2. During restraint horses experience restriction of movement and may additionally experience injuries and sensory overstimulation.

3. The welfare consequences during restraint primarily originate from the restraint itself, with hazards including inappropriate restraint by humans (forceful or prolonged), presence of slippery floor, inadequate design and inappropriate size of the stun box.

4.6. Conclusions for stunning

1. Penetrative captive bolt is the most commonly used stunning method for horses at slaughter. In some cases, firearms with free bullets are also used.

2. During the stunning process, animals might experience highly relevant WCs (e.g. injuries) and underlying negative affective states, i.e. pain and fear, if they are conscious (i.e. due to mis‐stunning or recovery of consciousness). ABMs can be used to monitor the state of consciousness.

3. A flowchart of ABMs related to the state of consciousness allows the monitoring of the stunning process (see Figure 5) at three key stages ((1) Interval between the stunning and shackling, (2) During neck cutting or sticking, (3) During bleeding).

4. Ineffective captive bolt stunning is mostly due to wrong shooting position and/or direction and/or inappropriate stunning parameters (such as bolt length, diameter, speed, penetration depth). Wrong shooting position is mainly due to the lack of proper facilities for restraining the horse body and head, leading to movements during the stunning application.

5. Using adequate captive bolt parameters (minimum bolt diameter of 9 mm, minimum bolt length of 8 cm and speed of at least 55 m/s) leads to effective stunning when all other factors dependent on the technique (such as position and direction of the shot) are applied correctly (certainty 66–100% – likely).

6. Ineffective firearm stunning is due to an incorrect position of the shot, inappropriate power and calibre of the cartridge or type of projectile.

7. The shooting position described (i.e. about 1 cm above the intersection point of a diagonal line from the centre of the eye to the centre of the base of the opposite ear, with the bolt targeting the brain stem) leads to effective stunning with captive bolt (certainty 66%–100% – likely) and with firearms (certainty 90%–100% – very likely).

4.7. Conclusions for bleeding

1. Hazards during bleeding are due to the lack of skilled operators and the use of blunt or too short knives, leading to the incomplete sectioning of the brachiocephalic trunk and/or of the carotid arteries, resulting in recovery of consciousness during bleeding and delayed onset of death.

2. Bleeding of ineffectively stunned animals and those recovering consciousness following stunning leads to severe pain and fear. The state of consciousness can be assessed during bleeding using the ABMs suggested (see the flowchart in Figure 5).

3. In addition, dressing alive animal leads to severe pain and fear. Death can be assessed by the combined use of the following ABMs: relaxed body, cessation of bleeding from the sticking wound and dilated pupils.

4. The shorter the stun‐to‐stick interval, the less likely the animals will start to recover consciousness following effective stunning.

5. A maximum stun‐to‐stick interval of 60 s prevents return to consciousness during bleeding (certainty 66%–100% – from likely to almost certain).

4.8. Conclusions related to the unacceptable methods and practices on welfare grounds

1. The EFSA experts consider the following practices unacceptable on welfare grounds as they induce severe pain:

• moving horses with mobility problems and/or signs of severe fatigue (see emergency slaughter in chapter 3.5);

• use of painful practices to move horses (e.g. electric goads, sticks) or restrain them (e.g. twitches);

• suspending or hoisting conscious animals;

• mechanical clamping or tying of the legs or feet;

• severing the spinal cord, such as using a puntilla or dagger;

• use of electric currents to immobilise the animal that do not stun or kill it under controlled circumstances, and, in particular, any electric current application that does not span the brain;

• sticking and bleeding of conscious horses.

5. RECOMMENDATIONS

5.1. General recommendations

1. The design, construction and maintenance of the premises and handling facilities should be tailored to horses' species‐specific behaviours and characteristics.

2. Since horses slaughtered for human consumption are primarily processed in cattle slaughterhouses, further research is necessary to adapt these facilities to better accommodate this animal species in relation to handling, movement, restraint, stunning and bleeding.

3. Even in well‐designed and properly equipped slaughterhouses, staff training is crucial to avoid hazards and prevent welfare consequences: all processes should be carried out by trained and skilled personnel. Staff should be educated to regard horses as sentient beings and to understand and accommodate the species and individual specific behaviours and characteristics.

4. The welfare status of horses should be monitored at each process of the slaughter by assessing the welfare consequences using ABMs.

5. The food business operator should put in place actions to prevent the occurrence of hazards. Such actions include:

   • regular inspection and maintenance of the facilities,
   • staff training and rotation,
   • proper equipment settings and usage,
   • preparedness for emergency slaughter without delay.

6. Slaughter practices considered unacceptable on welfare grounds must not be used.

5.2. Recommendations for arrival

1. At arrival, horses should be unloaded as soon as possible to mitigate the welfare consequences experienced during transit.

2. Deliveries should be strategically planned in coordination with suppliers and haulers to minimise waiting time before unloading at the slaughterhouse.

3. Temperature inside the vehicles at arrival (until unloading) should not exceed 25°C.

4. If horses exhibit signs of heat stress, mitigation measures should be applied, such as parking the vehicle in the shade, enhancing ventilation or offering water when drinkers are available on the vehicle.

5. When time off feed is longer than 12h, horses should be immediately slaughtered upon arrival or feed must be provided in lairage.

6. If horses exhibit signs of prolonged thirst, they should be slaughtered immediately upon arrival.

7. At arrival, if horses are experiencing restriction of movement due to lack of horizontal space (i.e. (i) for horses transported in group, stocking density above 200 kg/m²; 9ii) for horses transported individually less than 40 cm free space to the side of the horse at the widest point of the body or less than 40 cm in addition to the body length of the horse) or vertical space (e.g. less than 75 cm from the withers to the deck), they should be immediately unloaded.

5.3. Recommendations for unloading

1. Animals should be unloaded without delay and according to the transportation method: individually if transported in individual stalls, and in groups if transported in groups.

2. Horses should be handled by experienced handlers, who should allow horses to explore the surroundings (e.g. ramp) and take sufficient time to ensure a calm and correct unloading.

3. If it is not possible to unload a horse alone calmly, another horse could be unloaded first and used as demonstrator.

4. Pairs of mares and their unweaned foals should be unloaded together.

5. In order to prevent heat stress, the transport to the slaughterhouse should be planned to avoid any delays in unloading. In addition, to mitigate heat stress, the vehicle should be parked in the shade, or in an area where ventilation is ensured during the process.

6. Horses showing signs of severe restriction of movement and injuries (e.g. severe lameness, bone fractures, joint dislocations and open wounds) and/or are severely fatigued should be inspected by a veterinarian and/or trained professional and, if necessary, should be killed by emergency slaughter on the vehicle.

7. The unloading ramp should be adequate (i.e. slope with an angle of less than 20° and fitted with a system such as foot battens to facilitate foothold). The ramp should have side barriers, should be stable and not make loud noises when used. The ramp can be covered with straw, sand or sawdust to prevent slipping and reduce noise when used.

8. Loud noises from personnel (shouting), equipment or other animals (i.e. dogs barking) should be avoided during unloading. Ramps and passageways should have uniform lighting, with no strong light contrasts and/or shadows.

5.4. Recommendations for lairage

1. Mixing unfamiliar groups of horses in lairage should be avoided. It is recommended to keep familiar groups together from farm to slaughter or to house horses in individual pens in lairage, while also avoiding mixing sexes. Particularly, stallions should be kept in individual stalls.

2. Mares and their unweaned foals should be kept together in the same pen.

3. If horses kept in groups exhibit signs of group stress and injuries, the group should be immediately slaughtered after unloading or the horses should be housed individually, and aggressive animals isolated or slaughtered immediately.

4. In lairage the temperature should be kept below 25°C. Ventilation should be provided, if needed, to maintain this temperature. However, more research is needed to establish the optimal climatic conditions (e.g. temperature and humidity) to prevent heat stress in horses at lairage.

5. The lairage facility should be regularly cleaned to prevent slipping and falling.

6. Horses showing signs of severe restriction of movement and injuries (e.g. severe lameness, bone fractures, joint dislocations and open wounds) and/or are severely fatigued should be emergency slaughtered in the pen.

7. Drinking water must always be provided in lairage and be accessible to all horses.

8. Water troughs should be positioned along the walls rather than in the middle of the pen.

9. Horses experiencing the welfare consequence ‘prolonged hunger’ should be slaughtered without delay or feed should be provided if they are expected to stay in lairage for a long time (i.e. if the expected total time from the last meal exceeds 12h).

10. For horses lairaged in collective pens, adequate space should be provided, corresponding to a maximum stocking density of 110 kg/m².

11. For horses lairaged in individual stalls, adequate space should be provided, corresponding to 40 cm in addition to the maximum body width and 40 cm in addition to the body length.

12. A minimum vertical space of 2.7 m (floor‐to‐ceiling height) should be provided in lairage and adjusted for exceptionally tall animals.

13. For an appropriate design of the lairage area, partitions between pens and pen fences should include a solid lower part (up to approximately one meter) to avoid horse limbs being trapped. Pen fences and partitions should be high enough (i.e. above the withers) to prevent horses from escaping and getting injured. The floor should be solid, even, smooth, non‐slippery and with an adequate slope for water and urine evacuation; the floor should be covered with a good absorbent bedding material; variations in lighting should be avoided.

14. For animals housed individually, lairage pen fences should be high enough to prevent horses from escaping and getting injured while ensuring visual contact with other horses (e.g. solid partition from the floor for at least 1 m followed by tubular railings up to above the withers' height).

15. If a horse is expected to remain in lairage more than 12 h after arrival, suitable bedding must be provided.

16. Sudden noises, for instance vocalisation of animals, and noises from people or equipment (e.g. air compressors, air curtains) should be avoided.

17. Even illumination (e.g. without reflections) should be ensured to facilitate the movement of horses.

18. Using uncleaned pens that previously housed other species should be avoided. Pens should be cleaned thoroughly between different batches.

5.5. Recommendations for handling and moving

1. Mares and their unweaned foals should be moved together.

2. Passageways should have a width of about 80 cm for an average horse and the width may need to be adjusted for exceptionally large or small animals.

3. Painful or fearful stimuli, such as electric goads, hitting with a stick or shouting should not be used. Instead, the horses' natural behaviour to follow a conspecific should be used.

4. Handled animals should be moved either one by one with a halter and rope or in groups, and remain always in the sight of another animal.

5. Semi‐feral and unhandled horses should be moved in small groups or pairs.

5.6. Recommendations for restraint

1. Horses should be restrained appropriately avoiding using excessive force.

2. Animals should only be restrained when the operator is ready to stun them immediately and the duration of restraint should be as short as possible.

3. The size of the stun box should be adjusted to fit the horses, so that the animal cannot move back and forward or turn around.

4. The floor in the stun box should be kept clean and dry. It should be non‐slippery, flat or have a slight slope.

5.7. Recommendations for stunning

1. The recommended parameters for captive bolt stunning are: minimum bolt diameter of 9 mm, minimum bolt length of 8 cm and speed of at least 55 m/s. However, further research is needed to validate these parameters for all horse categories.

2. The correct shooting position for captive bolts and firearms is 1 cm above the intersection of a diagonal line extending from the centre of an eye to the centre of the opposite ear. The bolt should be directed towards the brain stem for maximum effectiveness.

3. More research is needed to find a suitable way to restraint the head of a horse to improve the effectiveness of captive bolt stunning in order to apply the correct shooting position.

4. To monitor stunning efficacy, the state of consciousness of the animals should be checked at three key stages (i.e. after stunning, just before sticking and during bleeding) using the recommended ABMs (Figure 5).

5. Animals should only be stunned when the operator is ready to bleed them immediately.

6. Animals ineffectively stunned or showing signs of recovering consciousness should be re‐stunned immediately in an appropriate way (e.g. adjusting the position or direction) or using a backup method.

5.8. Recommendations for bleeding

1. As soon as the horse is ejected from the stun box, the animal should be swiftly shackled and hoisted and a sharp knife, long enough to reach the brachiocephalic trunk, should be used to stick the animal promptly.

2. Continuous monitoring for signs of consciousness is imperative to confirm that the animal is unconscious during bleeding.

3. When using captive bolt stunning, immediate bleeding is essential to prevent the potential recovery of consciousness.

4. The stun‐to‐stick interval should be as short as possible, with a maximum of 60 s.

5. Monitoring for signs of death is essential to avoid dressing alive animals. Death should be confirmed before carcass processing begins.

6. Further research is required to investigate the possibility of false aneurysm formation at the severed ends of the carotid arteries in horses, which may contribute to the return to consciousness during bleeding.

ABBREVIATIONS

A

Ampere

ABM

animal‐based measure

EEG

electroencephalogram

EKE

Expert Knowledge Elicitation

Hz

Hertz

PCB

penetrative captive bolt

V

volt

WC

welfare consequence

WOAH

World Organisation for Animal Health

REQUESTOR

European Commission

QUESTION NUMBER

EFSA‐Q‐2023‐00310

COPYRIGHT FOR NON‐EFSA CONTENT

EFSA may include images or other content for which it does not hold copyright. In such cases, EFSA indicates the copyright holder, and users should seek permission to reproduce the content from the original source.

PANEL MEMBERS

Julio Alvarez, Anette Boklund, Sabine Dippel, Fernanda Dorea, Jordi Figuerola, Mette Herskin, Virginie Michel, Miguel Angel Miranda Chueca, Eleonora Nannoni, Søren Saxmose Nielsen, Romolo Nonno, Anja Riber, Karl Stahl, Jan Arend Stegeman, Hans‐Hermann Thulke, Frank Tuyttens, and Christoph Winckler.

Supporting information

Protocol for the development of the scientific opinion

APPENDIX A. Literature search outcomes for horses

A.1.

As described in Section 2.2.2, a literature search was carried out to identify peer‐reviewed scientific evidence on the topic of ‘slaughter and killing of horses’ that could provide information on the elements requested by the ToRs, i.e.: description of the processes, identification of hazards, origins, preventive and corrective measures, welfare consequences and indicators.

To obtain this, firstly a broad Literature Search was carried out, and the results were then screened and refined as described below.

Sources of information included in the search: Bibliographic database ‘Web of Science’.

The search string was designed to retrieve relevant documents to ‘animal welfare’ during ‘slaughter and killing’ of ‘horses’. Restrictions applied in the search string related to the processes characterising ‘slaughter and killing’ (from arrival to bleeding) of animals, and the date of publication (considering only those records published after EFSA, 2004). No language or document type restrictions were applied in the search string.

Refinement of literature search results

The search yielded a total of 94 records. Titles and abstracts were firstly screened to remove irrelevant publications (n = 30) (e.g. related to other species, processes or research purposes) and duplicates. A second screening allowed to identify their relevance to the topic. Most of the publications were related to transport of horses to slaughter but they focused on transport conditions, therefore they were considered irrelevant (n = 24).

The remaining publications focused on transport to slaughter, but in most the assessment was limited to the arrival process. These were excluded (n = 25) because already assessed in the previous opinion on the transport of Equidae (EFSA AHAW Panel, 2022b). Lastly, 15 references were selected as relevant (i.e. focusing on the horse slaughtering process) and considered in this assessment by reviewing the full papers:

1. EFSA AHAW Panel (2017)

2. EFSA AHAW Panel (2022b)

3. Fletcher et al. (2022)

4. Fletcher et al. (2023)

5. Gibson et al. (2014)

6. Messori et al. (2016)

7. Micera et al. (2010)

8. Miranda‐de la Lama et al. (2020)

9. Padalino et al. (2023)

10. Roy et al. (2015a)

11. Roy et al. (2015b)

12. Roy et al. (2019)

13. Roy et al. (2015c)

14. Weeks et al. (2012)

15. Werner & Gallo (2008)

APPENDIX B. Expert Knowledge Elicitation

B.1.

For the identification of highly relevant welfare consequences (sub‐question 2 in Annex A) a semi‐formal exercise for expert knowledge elicitation (EKE) was carried out. This involved the classification of welfare consequences by the experts first at individual level, followed by group discussion to identify the highly relevant ones by consensus.

The starting point was the list of 33 specific welfare consequences identified by the AHAW Panel in the methodological guidance produced in the context of the F2F strategy revision (for details see Section 3.1.1.3 in EFSA AHAW Panel, 2022).

The exercise consists of selecting the highly relevant welfare consequences out of these 33 for each of the following processes of Phase 1: lairage, handling, and moving and restraint.

For each process, the EFSA experts classified the 33 welfare consequences into four categories of relevance: (i) non‐applicable, e.g. the welfare consequence ‘Inability to perform suckling behaviour’ was not considered relevant for the animal categories covered by the mandate, (ii) slightly relevant, e.g. the welfare consequence ‘inability to perform play behaviour’ might apply, but its effect on welfare (in terms of prevalence and/or severity) was considered to be minimal compared to other welfare consequences of the slaughter process, (iii) moderately relevant and (iv) highly relevant.

Web of science search string a
Years 2004–2024
Search terms	Category
	Field searched
TS = horse OR TS = horses OR TS = equidae OR TS = equine OR TS = equines OR TS = “Equus ferus caballus”	Topic
AND
TS = slaughter* OR TS = kill* OR TS = stun* OR TS = captive bolt OR TS = captive‐bolt	Topic
AND
Arriv* OR *load* OR lairage* OR handl* OR mov* OR restrain* OR cut* OR bleed* OR conscious* OR pain* OR behav* OR stress*	Topic
AND
Welf* OR “animal welfare”	Topic

^a Date of the search: 15 April 2024.

The relevance was based on an estimate of the severity, duration and occurrence of each WC in each process (EFSA AHAW Panel, 2012a). Severity refers to the intensity of the welfare consequence. Duration refers to the time an animal spends within a specific process. Occurrence refers to the prevalence of animals experiencing the welfare consequence during that specific process.

Owing to the lack of published data, the EFSA experts expressed their qualitative expert opinion on these three parameters.

Expert opinion was elicited in three steps:

1. First step: the five EFSA experts individually screened the list of welfare consequences and identified those that would fall in the ‘non‐applicable’ or ‘slightly relevant’ categories. Their individual judgements were then collated, and those welfare consequences unanimously identified as belonging to these two categories were removed and not considered for further assessment. Those welfare consequences for which there was no consensus on whether they should be considered ‘non‐applicable’ or ‘less relevant’ remained for further assessment and required an open group discussion to find a consensus.

2. Second step: the experts individually screened the list of remaining welfare consequences and identified those that would fall in the category ‘highly relevant’ and should be kept for further assessment (Sub‐question 2). Similarly, as done during the first step in case discrepant opinions emerged, consensus was sought through group discussion.

3. Third step: the experts were asked to rank individually all the remaining welfare consequences in the list that were not already identified as highly relevant (and thus kept) or non‐applicable or slightly relevant (and thus removed) from the highest to the least relevant. Their individual rankings were then discussed again in an open group discussion to assign the remaining welfare consequences to the category ‘highly relevant’ or to the category ‘moderately relevant’.

The scientific opinion only reports, for each of the defined processes, those welfare consequences selected to be highly relevant from this exercise.

APPENDIX C. Sources of uncertainty

C.1.

Source of uncertainty	Nature or cause of the uncertainty	Impact of the uncertainty on the assessment
Expert group – number & type of experts	A limited number of experts (5) were selected based on the subject (slaughter of horses) and this may have resulted in a bias in the assessment processes.	The number of highly relevant welfare consequences (WC), ABMs and/or hazards may be incomplete.
Methodology for selection of highly relevant welfare consequences (per each slaughter phase/process)	The selection of highly relevant welfare consequences per each slaughter process was achieved by expert knowledge elicitation for which a predefined scale of relevance was used.	The highly relevant WCs may have been wrongly classified (a welfare consequence selected might have been included in error and similarly another welfare consequence might have been excluded in error)
Extensive literature search – Language	The search was performed exclusively in English (at least the abstract for other language sources). More studies might have been identified by including references with abstracts in languages other than English.	The ABMs and/or hazards may be incomplete.
Extensive literature search – Publication type	Studies considered included primary research studies identified through the extensive literature search and grey literature (factsheets, guidelines, conference papers, EU reports, book chapters, etc.) known to the EFSA experts, but an extensive search of the grey literature was not conducted, Therefore, there may be reports (grey literature) and other guidance documents on animal welfare of which the Working group is not aware of.	The listed ABMs and/or hazards may be incomplete.
Extensive literature search – Search strings	Although the search criteria were clearly reported some synonyms may not have been used in the search strings, and thus less hits might have been retrieved	The listed ABMs and/or hazards may be incomplete.
Extensive literature search – Source of studies	The search was limited to Web of Science Core Collection and four more specialist/subject‐specific databases (AGRICOLA, AGRIS, CABI – Animal Health & Production Compendium and MEDLINE). Although the search was complemented by internet searches and manual searches of the publicly available literature, no data were retrieved from other sources (e.g. industry data). More information could have been retrieved by applying a different methodology (e.g. public call for data).	The listed ABMs and/or hazards may be incomplete.
Extensive literature search – inclusion and exclusion criteria	A conservative approach was applied during the screening phase which could have led to the exclusion of certain studies that could have included relevant information	Incomplete overview of existing information. The ABMs and/or hazards may be incomplete.
Animal Species and Animal categories considered in the studies retrieved in the literature search	The animal breeds or categories used in the studies retrieved might not be the ones currently used in the EU to study WCs and ABMs, thus requiring an extrapolation exercise from the experts.	Underestimation of the magnitude of the WCs and related ABMs. Overestimation of the magnitude of the WCs in case the retrieved papers are specifically pointing to a specific category of horses.
Slaughter practices in the studies retrieved in the literature search	The studies retrieved through the literature search could have been performed anywhere in the world, and thus may consider slaughter conditions different from those currently allowed in the EU, also regarding animal welfare.	Underestimation/overestimation of the level of magnitude of the WCs and related hazards.

ANNEX A. Protocol for the development of the scientific opinion

A.1.

Annex A is available under the Supporting Information section on the online version of the scientific output.

EFSA AHAW Panel (EFSA Panel on Animal Health and Welfare) , Nielsen, S. S. , Alvarez, J. , Boklund, A. , Dippel, S. , Dorea, F. , Figuerola, J. , Herskin, M. , Miranda Chueca, M. A. , Nannoni, E. , Nonno, R. , Riber, A. , Stahl, K. , Stegeman, J. A. , Thulke, H.‐H. , Tuyttens, F. , Winckler, C. , Raj, M. , Velarde, A. , … Michel, V. (2025). Welfare of horses at slaughter. EFSA Journal, 23 (1), e9178. 10.2903/j.efsa.2025.9178