Reliability and Validity of UNESP-Botucatu Cattle Pain Scale and Cow Pain Scale in Bos taurus and Bos indicus Bulls to Assess Postoperative Pain of Surgical Orchiectomy

Abstract

Pain assessment guides decision-making in pain management and improves animal welfare. We aimed to investigate the reliability and validity of the UNESP-Botucatu cattle pain scale (UCAPS) and the cow pain scale (CPS) for postoperative pain assessment in Bos taurus (Angus) and Bos indicus (Nelore) bulls after castration.

Methods: Ten Nelore and nine Angus bulls were anaesthetised with xylazine-ketamine-diazepam-isoflurane-flunixin meglumine. Three-minute videos were recorded at -48 h, preoperative, after surgery, after rescue analgesia and at 24 h. Two evaluators assessed 95 randomised videos twice one month apart.

Results: There were no significant differences in the pain scores between breeds. Intra and inter-rater reliability varied from good (>0.70) to very good (>0.81) for all scales. The criterion validity showed a strong correlation (0.76-0.78) between the numerical rating scale and VAS versus UCAPS and CPS, and between UCAPS and CPS (0.76). The UCAPS and CPS were responsive; all items and total scores increased after surgery. Both scales were specific (81-85%) and sensitive (82-87%). The cut-off point for rescue analgesia was >4 for UCAPS and >3 for CPS.

Conclusions: The UCAPS and CPS are valid and reliable to assess postoperative pain in Bos taurus and Bos indicus bulls.

Keywords: animal behaviour; animal welfare; domestic cows; farm animals; pain assessment; pain measurement.

Figure 1

Timeline of the time-points used for the validation of the UNESP-Botucatu cattle pain scale (UCAPS) and the cow pain scale (CPS). Video recording was performed for 3 min at each time-point. Pain was assessed with the UCAPS, CPS, numerical rating scale (NRS) and visual analogue scale (VAS).

Figure 2

Occurrence frequency of each item’s score on the UNESP-Botucatu cattle pain scale (UCAPS). Percentage of the scores for each item and sum of occurrence for each item of the miscellaneous behaviours. Time-points: M0, 48 h before surgery and before fasting; M1, before sedation, during fasting (48 h after M0); M2, after surgery, three hours after animals were in sternal recumbency, followed by analgesia with morphine; M3, one hour after morphine; M4, 24 h after the end of surgery; GM, data of all time-points together (M0 + M1 + M2 + M3 + M4).

Figure 3

Occurrence frequency of each item’s score on the cow pain scale (CPS). Percentage of the scores for each item. Time-points: M0, 48 h before surgery and before fasting; M1, before sedation, during fasting (48 h after M0); M2, after surgery, three hours after animals were in sternal recumbency, followed by analgesia with morphine; M3, one hour after morphine; M4, 24 h after the end of surgery; GM, data of all time-points together (M0 + M1 + M2 + M3 + M4).

Figure 4

Biplot of the principal components analysis of the UNESP-Botucatu cattle pain scale (UCAPS). Confidence ellipses were built according to the time-points and pain scores. Time-points: M0, 48 h before surgery and before fasting; M1, before sedation, during fasting (48 h after M0); M2, after surgery, three hours after animals were in sternal recumbency, followed by analgesia with morphine; M3, one hour after morphine; M4, 24 h after the end of surgery. Ellipses were constructed according to the pain assessment time-points (M0 black, M1 green, M2 red, M3 blue and M4 yellow). The ellipse referring to the time when animals were suffering pain (M2) was positioned on the right side of the figure; on the opposite side are the ellipses corresponding to the time-points in which animals were pain-free (M0 and M1), where items showed lower scores. The time-point of moderate pain (M4) is positioned on the right side closer to the centre. All items on the scale are influenced by time-points of pain (M2 and M3) as their vectors are positioned in the direction of these ellipses and demonstrated higher pain scores.

Figure 5

Biplot of the principal components analysis of the cow pain scale (CPS). Confidence ellipses were built according to the time-points and pain scores. Time-points: M0, 48 h before surgery and before fasting; M1, before sedation, during fasting (48 h after M0); M2, after surgery, three hours after animals were in sternal recumbency, followed by analgesia with morphine; M3, one hour after morphine; M4, 24 h after the end of surgery. Ellipses were constructed according to the pain assessment time-points (M0 black, M1 green, M2 red, M3 blue and M4 yellow). The ellipse referring to the time when animals were suffering pain (M2) was positioned on the right side of the figure; on the opposite side are the ellipses corresponding to the time-points in which animals were pain-free (M0 and M1), where items showed lower scores. The time-point of moderate pain (M4) is positioned on the right side closer to the centre. All items on the scale are influenced by time-points of pain (M2 and M3) as their vectors are positioned in the direction of these ellipses and demonstrated higher pain scores.

Figure 6

Violin and box plot of the UNESP-Botucatu cattle pain scale (UCAPS) and cow pain scale (CPS) over time-points. (A) UCAPS total score; (B) CPS total score. The violin contour represents the dispersion data density together (both evaluators’ data), with the wider contour representing greater data density; the lower and upper bounds of the box, respectively, represent the first and third quartiles of data; the horizontal line plus space inside the box indicate the median; the red diamond indicates the average of each piece of time-point data separately; black circles indicate outliers. Different lowercase letters indicate statistical differences over the time-points (a > b > c > d); multiple comparisons were conducted by a linear mixed model with post-test corrected by Bonferroni procedure (p < 0.05). Time-points: M0, 48 h before surgery and before fasting; M1, before sedation, during fasting (48 h after M0); M2, after surgery, three hours after animals were in sternal recumbency, followed by analgesia with morphine; M3, one hour after morphine; M4, 24 h after the end of surgery.

Figure 7

Smooth line to total sum of the UNESP-Botucatu cattle pain scale (UCAPS) and cow pain scale (CPS) over the time-points for each phase, evaluator, breed and animal. (A) UCAPS, for phases 1 and 2. (B) CPS, for phases 1 and 2. (C) UCAPS, for evaluators 1 and 2. (D) CPS, for evaluators 1 and 2. (E) UCAPS, for Angus and Nelore. (F) CPS, for Angus and Nelore. (G) UCAPS, for each animal individually. (H) CPS, for each animal individually. The smooth lines were created automatically by the loess method; the grey area represents the standard error of the smooth line. Time-points: M0, 48 h before surgery and before fasting; M1, before sedation, during fasting (48 h after M0); M2, after surgery, three hours after animals were in sternal recumbency, followed by analgesia with morphine; M3, one hour after morphine; M4, 24 h after the end of surgery.

Figure 8

Two-graph ROC curve with the diagnostic uncertainty zone and ROC curve with AUC for the UNESP-Botucatu cattle pain scale (UCAPS). ROC (receiver operating characteristic) curve with a 95% confidence interval (CI) calculated from 1001 replications and area under the curve (AUC) [16]. The interpretation of an AUC ≥ 0.95 indicates a high discriminatory ability. Two-graph ROC curve, CI of 1001 replications, and of sensitivity and specificity >0.90 were applied to estimate the diagnostic uncertainty zone of the cut-off point of all evaluators, according to the Youden index for the UCAPS [42,43]. The diagnostic uncertainty zone was 5–6; <4 indicates pain-free animals (true negative) and >5 indicates animals suffering pain (true positive). The Youden index was >4, representative of the cut-off point for the indication of rescue analgesia.

Figure 9

Two-graph ROC curve with the diagnostic uncertainty zone, and ROC curve with AUC for the cow pain scale (CPS). ROC (receiver operating characteristic) curve with a 95% confidence interval (CI) calculated from 1001 replications and area under the curve (AUC) [16]. Interpretation of AUC ≥ 0.95 indicates high discriminatory ability. Two-graph ROC curve, CI of 1001 replications, and of sensitivity and specificity >0.90 applied to estimate the diagnostic uncertainty zone of the cut-off point of all evaluators, according to the Youden index for the UCAPS [42,43]. The diagnostic uncertainty zone was 3–4; <3 indicates pain-free animals (true negative) and >4 indicates animals suffering pain (true positive). The Youden index was >3, representative of the cut-off point for the indication of rescue analgesia.