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. 2020 Mar 2;10(3):412.
doi: 10.3390/ani10030412.

Is the Piglet Grimace Scale (PGS) a Useful Welfare Indicator to Assess Pain after Cryptorchidectomy in Growing Pigs?

Cecilia Vullo  1 , Sara Barbieri  2 , Giuseppe Catone  3 , Jean-Marie Graïc  4 , Marco Magaletti  5 , Ambra Di Rosa  3 , Ambra Motta  2 , Carlo Tremolada  2 , Elisabetta Canali  2 , Emanuela Dalla Costa  2
Affiliations

Is the Piglet Grimace Scale (PGS) a Useful Welfare Indicator to Assess Pain after Cryptorchidectomy in Growing Pigs?

Cecilia Vullo et al. Animals (Basel). .

Abstract

Pig cryptorchidism is a congenital anomaly, which requires surgical intervention. Pain assessment in pig farming has some limitations and consumers are increasingly concerned about suffering linked to on-farm procedures. The PGS seems to be a promising tool for pain assessment in piglets, although it has not been investigated whether this tool is applicable to growing pigs. This study was designed to determine whether the PGS could be useful to assess pain in growing pigs undergoing on-farm cryptorchidectomy. Ten mixed-breed cryptorchid pigs were pre-medicated with azaperone and ketamine. Anesthesia was induced and maintained using IV sodium based. Pigs were filmed pre- and 6 h post-surgery to evaluate their behavior (scan sampling every minute). Besides, 36 pictures of the face expressions (18 pre- and 18 6 h post-surgery) were scored with the PGS by three treatment-blind observers. The pre-surgery pig's activity ratio was 59%, while it was 2% 6 h post-surgery. While the PGS inter-observer reliability was excellent (Interclass Correlation Coefficient value of 0.87), the PGS score increased significantly in pigs 6 h post-surgery (Paired sample t-test, p = 0.02). The PGS proved to be a potentially effective method to assess pain associated with cryptorchidectomy. However, further validation studies are required to validate this tool for other potentially painful procedures.

Keywords: behavior; castration; pain; pain assessment; pig; piglet grimace scale.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
The handout distributed to Piglet Grimace Scale (PGS) assessors with images and explanations for each of the 3 Facial Action Units (FAUs). Ear position and check tightening/nose bulge is scored according to whether it is not present (0), moderately present (1), and obliviously present (2). While orbital tightening is scores on a 2-point scale: Not present (0), present (1).
Figure 2
Figure 2
The PGS score is presented on the y-axis (mean ± 1 SD) with the pre- and 6 h post-surgery recordings on the x-axis (Paired sample t-test; * p = 0.02).
Figure 3
Figure 3
Mean scan percentages (±1 SD) of activity and inactivity of pigs pre- and 6 h post-surgery. (Wilcoxon test; ** p = 0.000).
See this image and copyright information in PMC

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