Skip to main content
NCBI home page
Journal of Animal Science logoLink to Journal of Animal Science
. 2022 Mar 9;100(4):skac072. doi: 10.1093/jas/skac072

Technical Note: Validation of the effectiveness of electric stunning for euthanasia of mature swine (Sus scrofa domesticus)

Scott A Kramer 1, Brooklyn K Wagner 2, Steve J Moeller 3, Andrew S Bowman 4, Justin D Kieffer 3, Andréia Gonçalves Arruda 4, Michael D Cressman 3, Monique D Pairis-Garcia 2,✉
PMCID: PMC9030131  PMID: 35262702

Abstract

Electrocution and the use of a penetrating captive bolt gun (PCBG) are both acceptable methods of euthanasia for market weight swine. Research has demonstrated that a PCBG is effective in both growing and mature swine. Given limited to no published research base on electrocution in mature swine, the objectives of the present study were to evaluate the efficacy of a two-stage (head only followed by head to heart, 10 s contact for each) mobile electric stunner (E-STUN, Hubert HAAS TBG 96N) and to assess euthanasia outcomes when comparing E-STUN with the frontal placement of a heavy-duty PCBG (Jarvis, In-line Cylinder Style) when applied to heavy-weight (>200 kg) mature boars and sows. Effectiveness of the E-STUN and PCBG was evaluated first in unconscious anesthetized mature swine (n = 7 boars and sows per treatment; average weight 282 ± 48 kg, n = 28) to reduce the risk of failure in a conscious animal and then in conscious mature swine (n = 3 boars and sows per treatment; average weight 282 ± 63 kg, n = 12). Data from both stages were combined for analyses. Treatment efficacy was defined as any pig that achieved cardiac and respiratory arrest within 10 min after treatment application. A three-point traumatic brain injury score (0 = normal; 1 = some abnormalities; and 2 = grossly abnormal, unrecognizable) was used to evaluate six neuroanatomical structures (cerebral cortex, cerebellum, hypothalamus, thalamus, pons, and brain stem), and the presence of intracranial hemorrhage was also noted. All animals were immediately rendered insensible with E-STUN and PCBG, and no difference was noted between treatments for the detection of corneal reflex following treatment application (P = 0.11). Rhythmic breathing was absent following the administration of either E-STUN or PCBG. When evaluating the time to last heartbeat, there was a significant interaction between sex and treatment. Boars euthanized via E-STUN had a 346.8-s decrease in time to last heartbeat compared with boars euthanized via PCBG (P < 0.001), and females euthanized via E-STUN had a 479.3-s decrease in time to last heartbeat compared with females euthanized via PCBG (P < 0.001). Intracranial hemorrhage was common for both methods, and visible disruption of neural tissue was evident due to the physical nature of the PCBG. This study demonstrated that a mobile E-STUN system is as effective as a heavy-duty PCBG in inducing insensibility and death and shows promise as an alternative method for euthanizing mature pigs on-farm.

Keywords: electrical stunning, euthanasia, mature swine

Lay Summary

Euthanasia is a moral obligation of all individuals working in the swine industry. A majority of acceptable methods have been validated for market weight pigs, while less attention has focused on heavy-weight mature boars and sows. The objectives of the current study were to evaluate the effectiveness of a mobile electric stunner (E-STUN) as a method of humane euthanasia in heavy-weight mature boars and sows and to assess the outcomes when compared with a penetrating captive bolt gun (PCBG) method. The efficacy of the treatment was defined as any pig that achieved cardiac and respiratory arrest within 10 min after treatment application. The amount of traumatic brain injury was evaluated across the brain, and the presence of intracranial hemorrhage was also noted. All animals were immediately rendered insensible, and rhythmic breathing was absent following either treatment application. Boars and sows had a decreased time to last heartbeat with the E-STUN when compared with the PCBG method. Intracranial hemorrhage was common for both methods, and visible disruption of brain tissue was evident due to the physical nature of the PCBG. This study demonstrated that a mobile E-STUN is as effective as a PCBG for humane euthanasia of heavy-weight mature swine.

A limited number of safe and reliable euthanasia methods have been documented and validated for mature boars and sows. This study evaluates the efficacy of a mobile electrical stunning device as a method of euthanasia for heavy-weight mature boars and sows.

Introduction

Humane euthanasia remains a moral obligation of all individuals involved in the swine industry and represents a process in which the animal is immediately rendered insensible and dies with minimal stress and pain (National Pork Board, 2011; Shearer, 2016). While multiple euthanasia techniques have been described and utilized in swine, the reliability, consistency, and effectiveness of each technique are essential to ensuring effective euthanasia outcomes for pigs (Woods et al., 2013; Mullins et al., 2017; Anderson et al., 2019). When identifying an ideal euthanasia method, producers and veterinarians must take into account multiple considerations, including pig age, weight, operator safety, cost, practicality, aesthetics, legal requirements, and environmental impacts (Sivula and Suckow, 2018). The approved methods for euthanasia specific to swine may cause death by three different means, including 1) induction of hypoxia (gas mixtures and exsanguination as an adjunct method), 2) direct depression of the central nervous system (carbon dioxide and anesthetic overdose), and 3) physical destruction of neural tissue essential for life (manual blunt force trauma, non-penetrating captive bolt, penetrating captive bolt gun, firearm, and electrocution) (Leary et al., 2020).

The majority of research and recommendations have been made for immature to market weight swine, and a limited number of safe and reliable euthanasia methods have been documented and validated for mature boars and sows (Irwin et al., 2009; National Pork Board, 2011). Euthanasia of mature swine has its unique challenges due to distinct age- and gender-specific anatomical features as well as physical production system challenges including unique housing and management systems (Humane Slaughter Association, 2013; Woods et al., 2013). Of the limited number of safe and reliable euthanasia methods that have been documented and validated for mature swine, frontal placement of either a gunshot or PCBG and head-to-heart electrocution represent the most common techniques performed on-farm (Irwin et al., 2009; National Pork Board, 2011). In a recent publication from this lab, Kramer et al. (2021) demonstrated the efficacy of a heavy-duty cylinder-style PCBG for use in both mature boars and sows greater than 200 kg.

Electrocution is an acceptable euthanasia method for swine when performed in accordance with established euthanasia guidelines (Sparrey and Wotton, 1997; Irwin et al., 2009, National Pork Board, 2011) but is not as commonly utilized on-farm compared with PCBG or gunshot. Euthanasia via electrocution can be performed by impacting one point (head only; reversible) or two points (head to heart; irreversible) (National Pork Board, 2011). In head-only E-STUN, proper placement of the stunning device ensures the path of electric current through the brain resulting in tonic/clonic epileptiform activity and immediate insensibility (Grandin, 1985; McKinstry and Anil, 2004; Denicourt et al., 2010). Head-only E-STUN is a reversible procedure that is only optimally effective in maintaining insensibility for approximately 15 s post-stun completion and, therefore, must be followed by an adjunct step such as exsanguination to ensure death (Vogel et al., 2011). Head-to-heart E-STUN simultaneously stuns at the level of the brain and heart, resulting in immediate insensibility, ventricular fibrillation, cardiac arrest, and death (Vogel et al., 2011).

Electrical stunning equipment should supply sufficient amperage (A) to ensure that the animal will be rendered immediately insensible. Previous work suggests that a current of 1.25 to 1.3 A for a minimum of 3 s is required for a successful stun for market weight pigs (Hoenderken, 1983, Gregory, 1998; EFSA, 2004; Review of the Welfare of Animals in Agriculture, 2007; Spencer and Veary, 2010; Electrical Stunning of Red Meat Animals, 2013), while it has been suggested that mature swine (200 to 350 kg) require a current of at least 1.8 to 2.0 A (Review of the Welfare of Animals in Agriculture, 2007; von Wenzlawowicz, 2009; von Wenzlawowicz, et al., 2012). We hypothesize that a mobile E-STUN device delivering 2.2 to 2.4 A output is effective for euthanasia of heavy-weight (>200 kg) mature boars and sows. The objective of this study was to evaluate the efficacy of a mobile E-STUN device in achieving insensibility and death in heavy-weight (>200 kg) mature boars and sows when compared with a previously validated heavy-duty PCBG applied in the frontal position.

Materials and Methods

The protocol was approved by The Ohio State University Institutional Animal Care and Use Committee (IACUC) (no. 2020A00000031). The present study was carried out in accordance with the Guide for the Care and Use of Agricultural Animals in Research and Teaching (American Dairy Science Association, American Society of Animal Science and Poultry Science Association, 2010).

A two-stage experimental design was used in pursuit of this objective. In stage one, the effectiveness of the euthanasia techniques was verified in anesthetized mature swine (n = 7 boars and sows per treatment; average weight 282 ± 48 kg, n = 28) assuring the ability to measure an effective response while avoiding the potential for failure in a conscious animal. Animals were restrained using sort panels and anesthetized utilizing a single intramuscular injection of three anesthetic agents (xylazine, 4.4 mg/kg, AnaSed LA, VetOne, MWI Boise, ID, USA; ketamine HCl, 2.2 mg/kg, Ketathesia, Henry Schein Animal Health, Dublin, OH, USA; and tiletamine zolazepam HCl, 4.4 mg/kg, Tilzolan, Dechra Veterinary Products, Overland Park, KS, USA; Pairis-Garcia et al., 2014).

Stage two was then performed to identify and validate the effectiveness of the euthanasia techniques in conscious mature swine (n = 3 boars and sows per treatment; average weight 282 ± 63 kg, n = 12). Conscious mature boars and sows were restrained using a dual hinged (0.66 m width × 2.13 m length × 1.2 m height), solid-sided, non-current conducting barrier affixed to a solid masonry block wall at the front. Pigs were walked into the stun area, and a solid, non-current conducting barrier was used to prevent rearward movement. In a sequential two-step process, the stunner tongs were first applied across the head behind the eyes (head only) for 10 s, after which the pig was in a lateral recumbent position. The hinged barrier was opened, and the stunning tongs were rapidly applied spanning from the more ventral aspect of the ribcage to the head (head to heart) while in lateral recumbency from for 10 s (Figure 1). The 10 s represented the fixed instrumentation and timing of the E-STUN during use. Conscious swine were restrained using a common pig snare prior to the implementation of the PCBG euthanasia treatment. A more detailed description of methods and materials utilized herein are described in an associated manuscript, Kramer et al. (2021).

Figure 1.

Figure 1.

Open in a new tab

The images represent the proper placement of stunning tong electrodes for (a) head-only and (b) head-to-heart stunning. A sequential two-step process: head-only followed by head-to-heart stunning may be utilized for euthanasia in swine. Initially, the electrodes are placed on the pig’s head between the eye and ear in a manner that, upon initiation, would allow the current to pass through the brain inducing immediate insensibility. The second step consists of simultaneously placing an electrode on the head and on the thorax distal to the point of the olecranon. Upon initiation, the electrical current induces cardiac fibrillation and death.

Euthanasia equipment

Electric stunner

A TBG 96/N mobile E-STUN (Hubert HAAS, Neuler, Germany; 230 V, 50 Hz operating current, 230 to 400 V output voltage, 2.2 to 2.4 A output at switch setting 3) fitted with the standard, scissor-design stunning tongs with 78.74 cm (31 in) length and 60.96 cm (24 in) span was evaluated. The stunning device included an integrated voltage and electrical current output display, with an optical and acoustic signal to indicate electric flow and completion of the timed stun phase.

Penetrating captive bolt gun

The PCBG used was a Super Heavy-Duty Jarvis In-line Cylinder-Style Power Actuated Stunner Stunner/0.25S with a bolt diameter of 11.4 mm (0.45 in), a bolt extension length of 14.6 cm (5.75 in), and a power load of 6 grains (Part #: 4144059/Serial #: 148193, Item #: 302877315 BUNZL Processor Division/Koch Supplies, Riverside, MO). The penetration depth of the cylinder style can reach up to 11.43 to 12.7 cm (4.50 to 5.00 in) with a maximum load of 6 grains (Kramer et al., 2021). This equipment was previously validated as effectively applied in the frontal position for mature swine (Kramer et al., 2021).

Evaluation of treatment efficacy

Immediately following treatment application, insensibility was evaluated by assessing the presence/absence of a corneal reflex and quantifying the presence of rhythmic respiration and heartbeat. Death was confirmed and defined as any pig that achieved cardiac and respiratory arrest within 10 min of treatment application. Respiratory arrest was confirmed by visual assessment of respiratory cessation of the chest cavity, while cardiac arrest was confirmed by the time to last heartbeat assessed as time to non-detectable waveform on a pulse oximeter placed on the animal’s tongue (SurgiVet Advisor Vital Signs Monitor Code V9204, Smiths Medical ASD, Inc., St. Paul, MN). Placement of the pulse oximeter probe and recording of time to last detectable heartbeat began as soon as physically possible following the euthanasia technique. After death was confirmed, the carcass was shackled, hoisted, and exsanguinated before the removal of the head. The head was split into two sagittal sections using a band saw. Skull thickness was measured and brain tissue was scored for hemorrhage and traumatic brain injury (TBI). Frontal, parietal, temporal, and occipital regions of the brain were scored for hemorrhage (presence of hemorrhage = 1, absence of hemorrhage = 0). The TBI scores were assigned to the cerebral cortex, thalamus, hypothalamus, pons, cerebellum, and brain stem brain using a 3-point scale (0 = normal; 1 = some abnormalities; and 2 = grossly abnormal, unrecognizable). Scoring systems were adapted from Woods (2012).

Statistical analysis

Statistical analysis was conducted using STATA IC 14 (College Station, TX, USA). Basic descriptive statistics were used to describe demographics for the study population, which included mean and SD for continuous variables (weight, skull thickness, and TBI) and frequency distributions (proportions and percentages) for categorical variables (sex and hemorrhage scores).

Animal was the experimental unit in all analyses. In order to evaluate the efficacy of the two treatments (E-STUN and PCBG) in achieving insensibility and death in mature boars and sows, three main outcomes were separately assessed: presence of corneal reflex (yes or no), presence of rhythmic respiration (yes or no), and time to last heartbeat (continuous, s). In addition to the two euthanasia treatments of interest, other predictors considered in all models included whether the animal was anesthetized (yes or no, based on the study stages), sex (boar or sow), animal weight (continuous, kg), maximum skull thickness (continuous, mm), and the interaction between treatment and sex.

Multivariable logistic and linear models (depending on the outcome variable type) were built in a stepwise manner. For each model, firstly, the assumption of linearity was checked for all continuous variables of interest. If nonlinear relationships were observed, these variables were categorized using the median values. Secondly, the correlation between variables was assessed using the Spearman correlation coefficient and a cutoff value of 0.80 to declare highly correlated variables. Thirdly, univariable models were built separately for each predictor, and any variables with a P ≤ 0.20 or identified as potential confounders were selected to move forward to the multivariable model. Lastly, a multivariable model was built using a backward stepwise approach and a P-value cutoff of P ≤ 0.05 to determine statistical significance. Confounding variables were defined as variables changing other variable’s coefficients by more than 20% and were retained in final models regardless of statistical significance. Given the small sample size, for some of the outcomes, multivariable models were unable to yield estimates and, for those cases, either Chi-square or Fisher’s exact test was used and is presented, with the caveat that in those cases a multivariable model was not feasible.

Results

Both treatments were 100% effective in meeting the 10-min endpoint confirmation of death as verified by cardiac and respiratory arrest. Table 1 depicts basic descriptive statistics that were used to describe demographics for the study population, which included mean, SD for continuous variables, and frequency distributions for categorical variables. Intracranial hemorrhage was present across both treatments with substantial hemorrhage present on neural tissue associated with the PCBG treatment (Figure 2). Induction of insensibility was rapid, and the assessment of corneal reflex (P = 0.11) and rhythmic breathing (P = 1.00) was not different between treatments.

Table 1.

Means (SD) and frequency (number, percentage) for variables measured on swine (n = 20 females and n = 20 males) within electrocution (E-STUN) and penetrating captive bolt gun (PCBG) euthanasia treatments

Variables PCBG E-STUN
Continuous variables 
(mean, SD) n = 20, 10 males and 10 females n = 20, 10 males and 
10 females
 Maximum skull thickness (mm) 8.22 (1.23) 8.66 (0.69)
 TBI cerebellum 1.10 (0.31) 0.95 (0.22)
 TBI thalamus 1.15 (0.37) 0.05 (0.22)
 TBI hypothalamus 1.15 (0.37) 0.45 (0.51)
 TBI pons 1.15 (0.37) 0.75 (0.44)
 TBI cortex 1.35 (0.49) 1.00 (0.00)
 TBI brainstem 1.05 (0.22) 0.90 (0.31)
Categorical variables (number, %)
 Absence of hemorrhage parietal 1.00 (5.00) 0.00 (0.00)
 Absence of hemorrhage 
occipital 0.00 (0.00) 2.00 (10.00)
 Absence of hemorrhage 
temporal 1.00 (5.00) 2.00 (10.00)
 Absence of hemorrhage frontal 0.00 (0.00) 1.00 (5.00)
Open in a new tab

Traumatic brain injury (TBI) scores (0 = normal; 1 = some abnormalities; 
2 = grossly abnormal, unrecognizable) (Woods, 2012).

Figure 2.

Figure 2.

Open in a new tab

Example images depicting mid-sagittal sections of the porcine brain representing hemorrhage and traumatic brain injury following euthanasia of mature swine using either two-step (head only and head to heart) electrocution (a, b) or frontal placement of a heavy-duty penetrating captive bolt gun (c, d).

The final linear regression model did not include anesthesia status as it was not significant for any of the outcomes. Time to last heartbeat showed a significant interaction between sex and treatment (Figure 3). Within treatments, there were no statistical differences in time to last heartbeat between boars and sows. However, boars euthanized via E-STUN had a 346.8-s decrease in time to last heartbeat compared with boars euthanized via PCBG (P < 0.001), and females euthanized via E-STUN had a 479.3-s decrease in time to last heartbeat compared with females euthanized via PCBG (P < 0.001).

Figure 3.

Figure 3.

Open in a new tab

Adjusted predictions (95% confidence interval) for time to last heartbeat (s) indicated no difference between boars and sows within the treatment group but did reveal that boars euthanized via electrical stunning had a 346.8-s decrease in time to last heartbeat compared with boars euthanized via penetrating captive bolt gun (P < 0.001) and females euthanized via electrical stunning had a 479.3-s decrease in time to last heartbeat compared with females euthanized via penetrating captive bolt gun (P < 0.001).

Discussion

Historically, published research focused on humane and effective methods for euthanasia of mature swine has been inadequate and complicated as mature swine present unique challenges to current acceptable methods of euthanasia (Grandin, 1980; Kramer et al., 2021). Considering the limited availability of information, the objective of this study was to compare the efficacy of a mobile E-STUN to a heavy-duty PCBG in achieving insensibility and death in mature heavy-weight boars and sows. The knowledge gained in comparing these euthanasia techniques will provide essential information on achieving a humane death of mature swine on-farm that can be used to shape on-farm welfare standards specific to euthanasia.

This study confirmed that E-STUN for on-farm euthanasia of mature swine (>200 kg) using a two-step process (head only/head to heart) and supplying a maximum of 2.4 A is as effective as the use of heavy-duty PCBG. The E-STUN technique reliably induced insensibility and a more rapid time to last heartbeat, cardiac arrest, and death compared with the use of the PCBG for mature boars and sows. The data presented in this study are in agreement with Vogel et al. (2011), who reported that, in a slaughter setting (<130 kg pigs), a two-stage electrical stunning method supplying a mean current of 2.3 A using a standard head-only stun immediately followed by stunning wand application to the cardiac region of the chest ensured insensibility and abolishment of heartbeat, rhythmic breathing, natural blinking, eye tracking to a moving object, and righting reflex in pigs (<130 kg).

Practical consideration of utilizing electrocution for euthanasia emphasizes its inherent challenges. Electrocution is potentially dangerous to humans and other animals when applied in damp, metal-based enclosures and areas common to swine facilities. Electrocution may also be aesthetically unpleasing for the operator. In addition, appropriate training is required before the equipment can be operated safely, and proper placement of the electrodes is essential for an effective stun. If using a two-step E-STUN process, the timing between stuns must also be monitored to prevent unnecessary stress or pain for the animal. The TBG 96/N mobile E-STUN avoids hot-wanding as the contact area of the stunning tongs is not energized until applied firmly to the animal. Vogel et al. (2011) reported that a minimum of 3 s is required to induce unconsciousness during the head-only phase and is ideally effective for approximately 15 s. In the current study, the stunning tongs were held on the head for 10 s followed by immediate application of the stunning tongs spanning from the more ventral aspect of the ribcage to the head (head to heart), while in lateral recumbency for an additional 10 s effectively euthanizing the animal. The TBG 96/N mobile E-STUN may be equipped with one of three sizes of stunning tongs. In the current study, the standard size stunning tongs were successfully utilized for euthanasia of mature heavy-weight boars and sows; however, the larger-sized stunning tongs may provide a greater range of ergonomic options.

Electrical stunning equipment is very economical to operate, is easier to maintain than captive bolt equipment, and may be effective in certain conditions where no method is available to restrain the animal (Grandin, 1980). In addition, electrocution may be the ideal technique used for mitigating the biosecurity risk of blood-associated pathogen dispersal in an animal disease event given the process results in little to no blood loss by the animal and no limitations on carcass disposal (Arruda et al., 2020). However, commercial farms must have adequate capacity to attain sufficient amperage to induce an effective stun for this particular operating system.

In conclusion, a two-step E-STUN is an effective and reliable technique for on-farm euthanasia for mature swine. This technique is as effective as other common euthanasia techniques currently used on-farm and has the ability to safeguard animal welfare by eliminating pain and suffering in compromised pigs that warrant euthanasia.

Acknowledgment

We would like to acknowledge the National Pork Board/Pork Checkoff for wholly funding this project (grant 20-097).

Glossary

Abbreviations

A

amperage

E-STUN

electric stunner

PCBG

penetrating captive bolt gun

TBI

traumatic brain injury

Conflict of interest statement

S.A.K. is currently a Veterinary Medical Officer at the U.S. Department of Agriculture’s (USDA) Animal Plant Health Inspection Service. He is writing in a personal capacity and his activity, opinions, and views expressed herein are personal and not official. Disclaimer. The views expressed in this manuscript do not necessarily represent the views of the USDA Animal and Plant Health Inspection Service or the United States.

Literature Cited

  1. American Dairy Science Association, American Society of Animal Science and Poultry Science Association. 2010. Guide for the care and use of agricultural animals in research and teaching. 3rd ed. Champaign (IL): Fed. Anim. Sci. Soc. [Google Scholar]
  2. Anderson, K., Ries E., Backes J., Bishop K., Boll M., Branter E., Hinrichs B., Kirk A., Olsen H., Risius B., . et al. 2019. Relationship of captive bolt stunning location with basic tissue measurements and exposed cross-sectional brain area in cadaver heads from market pigs. Transl. Anim. Sci. 3:1405–1409. doi: 10.1093/tas/txz097 [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Arruda, A. G., Beyene T. J., Kieffer J., Lorbach J. N., Moeller S., and Bowman A. S.. . 2020. A systematic literature review on depopulation methods for swine. Animals. 10(11):2161. doi: 10.3390/ani10112161 [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Denicourt, M., Klopfenstein C., Dufour V., Pouliot F., and DʹAllaire S.. . 2010. Using an electrical approach to euthanize pigs on farm: fundamental principles to know. In: Proceedings of the 2010 AASVA Annual Meeting: Implementing Knowledge, March 6–9, 2010, Omaha, Nebraska. Perry, Iowa: American Association of Swine Veterinarians; p. 451–468. Available from https://www.aasv.org/library/swineinfo/item.php?AASV/2010/451.pdf. Accessed December 11, 2021. [Google Scholar]
  5. Electrical Stunning of Red Meat Animals. Guidance Notes No.: 4. Guidance on the use of electrical stunning equipment including electrical theory, restraint, effective stunning, bleeding and safety. 2013. Wheathampstead (UK). [Google Scholar]
  6. European Food Safety Authority (EFSA). 2004. Opinion of the Scientific Panel on Animal Health and Welfare (AHAW) on a request from the Commission related to welfare aspects of the main systems of stunning and killing the main commercial species of animals. EFSA J. 2(7):45. doi: 10.2903/j.efsa.2004.45 [DOI] [Google Scholar]
  7. Grandin, T. 1980. Mechanical, electrical and anesthetic stunning methods for livestock. Int. J. Study Anim. Probl. 1(4):242–263. [Google Scholar]
  8. Grandin, T. 1985. Cardiac arrest stunning of livestock and poultry. In: Fox, M. W., and Mickley L. D., editors. Advances in animal welfare science, Springer, Dordrecht, Netherlands; p. 1–30. [Google Scholar]
  9. Gregory, N. G. 1998. Animal welfare and meat science. Wallingford (UK): CABI Publishing. [DOI] [PubMed] [Google Scholar]
  10. Hoenderken, R. 1983. Electrical and carbon dioxide stunning of pigs for slaughter. In: Eikelenboon, G., editor. Stunning of animals for slaughter. Boston (MA): Martinus Nijhoff Publishers; p. 59–63. [Google Scholar]
  11. Humane Slaughter Association. 2013. Captive bolt stunning of livestock. 2013 edition. Wheathampstead (UK): Humane Slaughter Association. The Old School, Brewhouse Hill, Wheathampstead, Herts., AL4 8AN, UK. [Google Scholar]
  12. Irwin, C., Young G., Millman S. T., Daniels S., Niekamp S., and Ramirez A.. . 2009. Systematic review of swine euthanasia methods and welfare measures reported. J. Appl. Anim. Welf. Sci. 12(2):151–152. doi: 10.1080/10888700902720318 [DOI] [Google Scholar]
  13. Kramer, S. A., Wagner B. K., Robles I., Moeller S. J., Bowman A. S., Kieffer J. D., Arruda A. G., Cressman M. D., and Pairis-Garcia M. D.. . 2021. Validating the effectiveness of alternative euthanasia techniques using penetrating captive bolt guns in mature swine (Sus scrofa domesticus). J Anim Sci. 99(3):1–8, skab052. doi: 10.1093/jas/skab052 [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Leary, S., Underwood W., Anthony R., Cartner S., Grandin T., Greenacre C., Gwaltney-Brant S., Mccrackin M. A., Meyer R., Miller D., . et al. 2020. AVMA guidelines for the euthanasia of animals. 2020 edition. Schaumburg (IL): American Veterinary Medical Association (AVMA). [Google Scholar]
  15. McKinstry, J. L., and Anil M. H.. . 2004. The effect of repeat application of electrical stunning on the welfare of pigs. Meat Sci. 67:121–128. doi: 10.1016/j.meatsci.2003.10.002 [DOI] [PubMed] [Google Scholar]
  16. Mullins, C., Pairis-Garcia M., George K., Anthony R., Johnson A., Coleman G., and Millman S.. . 2017. Determination of swine euthanasia criteria and analysis of barriers to euthanasia in the United States using expert opinion. Anim. Welf. 26(4):449–459. doi: 10.7120/09627286.26.4.449 [DOI] [Google Scholar]
  17. National Pork Board. 2011. On-farm euthanasia of swine: recommendations for the producer. Des Moines (IA): National Pork Board. [Google Scholar]
  18. Pairis-Garcia, M. D., Johnson A. K., Millman S. T., Stalder K. J., and Karriker L. A.. . 2014. Effects of yohimbine, an alpha 2-antagonistic reversal agent, on physiological recovery parameters of anesthetized sows. J. Swine Health Prod. 22(1):16–23. [Google Scholar]
  19. Review of the Welfare of Animals in Agriculture: Hearing before the Subcommittee on Livestock, Dairy and Poultry of the Committee on Agriculture House of Representatives One Hundred Tenth Congress First Session. May 8, 2007, Serial No.: 110–118. Washington (DC): U.S. Government Printing Office; p. 236. [Google Scholar]
  20. Shearer, J. 2016. Timely euthanasia and impacts of euthanasia on caretakers. In: Proceedings of the AASV Annual Meeting: Standing on the shoulders of giants: Collaboration and teamwork, February 27–March 1, 2016, New Orleans, Louisiana. Perry, Iowa: American Association of Swine Veterinarians; p. 14–16. [Google Scholar]
  21. Sivula, C. P., and Suckow M. A.. . 2018. Euthanasia. In: Weichbrod R. H., Thompson G. A. H., and Norton J. N., editors. Management of animal care and use programs in research, education, and testing. 2nd ed. Boca Raton (FL): CRC Press/Taylor & Francis; p. 2. . [PubMed] [Google Scholar]
  22. Sparrey, J. M., and Wotton S. B.. . 1997. The design of pig stunning tong electrodes-a review. Meat Sci. 47(1/2):125–133. doi: 10.1016/S0309-1740(97)00047-8 [DOI] [PubMed] [Google Scholar]
  23. Spencer, B. T., and Veary C. M., . 2010. A study of preslaughter pig handling and stunning in selected South African Highveld Region abattoirs. J. S. Afr. Vet. Assoc. 81(2):102–109, a114. doi: 10.4102/jsava.v81i2.114 [DOI] [PubMed] [Google Scholar]
  24. Vogel, K. D., Badtram G., Claus J. R., Grandin T., Turpin S., Weyker R. E., and Voogd E.. . 2011. Head-only followed by cardiac arrest electrical stunning is an effective alternative to head-only electrical stunning in pigs. J. Anim. Sci. 89(5):1412–1418. doi: 10.2527/jas.2010-2920 [DOI] [PubMed] [Google Scholar]
  25. von Wenzlawowicz, M. 2009. Electrical stunning of sows and sheep. Dtsch. Tierärztl. Wochenschr. 116(3):107–109. [Google Scholar]
  26. von Wenzlawowicz, M., von Holleben K., and Eser E.. . 2012. Identifying reasons for stun failures in slaughterhouses for cattle and pigs: a field study. Anim. Welf. 21(1):51–60. doi: 10.7120/096272812X13353700593527 [DOI] [Google Scholar]
  27. Woods, J. 2012. Analysis of the use of the “CASH” Dispatch Kit captive bolt gun as a single stage euthanasia process for pigs [master’s thesis]. Graduate Theses and Dissertations. Ames (IA): Iowa State University. [Google Scholar]
  28. Woods, J., Shearer J. K., and Hill J.. . 2013. Chapter 10: Recommended on-farm euthanasia practices. In: Grandin, T., editor. Improving animal welfare. Colorado State University. Wallingford (UK): CABI Publishing; p. 186–213. [Google Scholar]

Articles from Journal of Animal Science are provided here courtesy of Oxford University Press

RESOURCES