Table 1.
Summary of pain assessment composite tools and facial scales.
| Species | Instrument | Focus | Description | References |
|---|---|---|---|---|
| Bovine | UNESP-Botucatu unidimensional pain scale for acute postoperative pain assessment in cattle | General behaviors | Developed in beef cattle (2–3 years-old) undergoing castration. Includes five items (locomotion, interactive behavior, activity, appetite, miscellaneous behaviors) scored from 0 to 2 for a total score of 10. Analgesic threshold: >4/10 The UNESP-Botucatu unidimensional pain scale for acute postoperative pain assessment in cattle has also been validated in Italian. |
[35], [46] |
| Cow Pain Scale | General behaviors and facial expressions | Developed in adult dairy cattle (unclear age) with naturally-occurring medical or surgical painful conditions. Includes six items. Attention towards the surroundings and facial expression are scored from 0 to 1. Head position, ears position, response to approach, and back position are scored from 0 to 2 for a total score of 10. An analgesic threshold (3/10) is subjectively suggested. However, it has not been defined based on statistical calculations. | [42] | |
| Sheep | The UNESP-Botucatu sheep acute composite pain scale (USAPS) | General behaviors | Developed in adult sheep (3.5 ± 1.8 years-old) undergoing elective laparoscopy. Includes six items (interaction, locomotion, head position, posture, activity, appetite) scored from 0 to 2 for a total score of 12. Analgesic threshold: ≥4/12. | [41] |
| Sheep Grimace Scale | Facial expressions | Developed in adult laboratory sheep (unclear age) undergoing tibial osteotomy. Includes three items. Orbital tightening and ear & head position are scored from 0 to 2. Flehmen is scored from 0 to 3 for a total of 7. | [40] | |
| Sheep Pain Facial Expression Scale | Facial expressions | Developed in sheep (>1 year-old) with footrot or mastitis. Includes five items (abnormal ear position, orbital tightening, abnormal nostril and philtrum shape, cheek tightening, abnormal lip and jaw profile) scored from 0 to 2 for a total of 10. No analgesic threshold available. | [47] | |
| Lamb Grimace Scale | Facial expressions | Developed in lamb (5–6 weeks-old) undergoing tail docking. Includes five items (ear position, orbital tightening, nose changes, cheek flattening, mouth change) scored from 0 to 2. No analgesic threshold available. | [48] | |
| Swine | UNESP-Botucatu pig composite acute pain scale (UPAPS) | General behaviors | Developed in growing pigs (38 ± 3 days-old) undergoing castration. Includes six items (attention to affected area, locomotion, activity, appetite, interactive behaviour and miscellaneous) scored from 0 to 3 for a total of 18. Analgesic threshold: ≥6/18. | [45] |
| Sow Grimace Scale | Facial expressions | Developed in sows (unclear age; gilts and multiparous sows) undergoing farrowing. Includes five items (tension above eyes, snout angle, neck tension, temporal tension and ear position, cheek tension) scored from 0 to 2 for a total score of 10. No analgesic threshold available. | [44], [49,50] | |
| Piglet Grimace Scale (PGS)—a | Facial expressions | Developed in piglets (5 days-old) undergoing castration. Includes three items. Ears and cheek bulging/nose bulge are scored from 0 to 2. Orbital tightening is scored from 0 to 1 for a total of 5. No analgesic threshold available. Obs 1: The PGS was validated in growing pigs (73 ± 11 days-old) undergoing castration and laparotomy due to unilateral cryptorchidism [51]. Obs 2: In two studies assessing the responsiveness of the PGS to buprenorphine, meloxicam and ketoprofen in piglets undergoing castration [52,53]; the item ‘ears’ were scored from 0 to 3 for a total score of 6. |
[50] | |
| Piglet Grimace Scale—b | Facial expressions | Developed in piglets (3 days-old) undergoing tail docking and castration. Includes seven items (temporal tension, forehead, eyes, tension above the eyes, cheek, snout plate, snout angle, lip, jaw, and nostril) scored from 0 to 2. Each item is evaluated independently and there is no final score. No analgesic threshold is available. | [43] |
References in bold refer to the study reporting the development and initial validation of the scale. Additional references refer to subsequent studies.