A comparison of behavioural methodologies utilised to quantify deviations in piglet behaviour associated with castration

Abstract

Surgical castration is a painful procedure that is routinely performed without pain relief on commercial pig (Sus scrofa domesticus) farms. Previous research has focused on quantifying piglet pain response through behaviours. However, to date, behavioural sampling methodologies used to quantify pain associated with castration have not been validated. Therefore, the objective of this study was to validate scan sampling methodologies (2-min, 3-min, 5-min, 10-min and 15-min intervals) to quantify piglet pain responses expressed by castrated piglets behaviour. A total of 39 Yorkshire-Landrace × Duroc male piglets (five days of age) were surgically castrated using a scalpel blade. Behaviour frequency and duration (scratching, spasms, stiffness, tail wagging and trembling) of each piglet were continuously collected for the first 15 min of the following hours relative to castration (–24, 1–8 and 24). To determine if the sampling interval accurately reflected true duration and frequency for each behaviour, as determined by continuous observation, criteria previously utilised from other behavioural validation studies were used: coefficient of determination above 0.9, slope not statistically different from one and intercept not statistically different from zero. No scan sampling interval provided accurate estimates for any behavioural indicators of pain. The results of this study suggest that continuous sampling is the most appropriate methodology to fully capture behaviour specific to pain associated with castration. Using validated behavioural methodologies in future research can assist in the development of objective, science-based protocols for managing pig pain.

Non-Steroidal Anti-Inflammatory Drugs: Pharmacokinetics and Mitigation of Procedural-Pain in Cattle

“…Given that no physiological biomarkers for pain have been reliably identified and agreed upon, many experts are choosing to explore behavioral pain assessments. For example, behavioral assessment methodologies were recently evaluated for quantifying behavioral deviations as indicators of pain in castrated piglets [ 71 ]. Moreover, this work uncovered only one method that could be validated amongst several techniques used in previous studies, highlighting the need for proactive validation of pain assessment methodologies [ 71 ].…”

“…For example, behavioral assessment methodologies were recently evaluated for quantifying behavioral deviations as indicators of pain in castrated piglets [ 71 ]. Moreover, this work uncovered only one method that could be validated amongst several techniques used in previous studies, highlighting the need for proactive validation of pain assessment methodologies [ 71 ]. Moving forward, refined and scientifically validated pain assessment methodologies for cattle are needed to facilitate reliable drug efficacy evaluation techniques required for continued progress in pain mitigation research and to obtain U.S. FDA approval of an effective drug for controlling procedural pain.…”

Observing Brief and Irregular Behaviour of Animals—The Validity of Short Observation Periods

“…As different studies have demonstrated, behaviour can be efficiently and accurately estimated using scan sampling for behaviour with a long duration (e.g., resting) [4,6,[8][9][10][11] or time sampling for behaviour with a moderate duration (e.g., feeding and locomotion) [3,8]. However, in other studies on pigs, it was not possible to accurately estimate different behaviour with short duration using scan sampling, such as pain associated behaviour [12] or agonistic or sexual behaviour [9]. Hence, the validity of observations of short-term and irregular behaviour should be investigated in greater detail to approve results of existing studies and to determine optimal observation techniques for future studies.…”

“…However, shortening the interval as far as to accurately estimate biting behaviour (e.g., scan sampling every 5 s) would be less efficient than using continuous sampling. Thus, time sampling or continuous sampling is recommended to observe short behaviour such as biting behaviour in pigs [5,[9][10][11][12], although there is no recommendation regarding the required observation length. The observation time per day is often determined by practical factors and rarely exceeds 2 h per day [13][14][15][16][17][18].…”

Identifying Barriers to Implementing Pain Management for Piglet Castration: A Focus Group of Swine Veterinarians

“…Quantifying pain associated with castration has been primarily conducted by evaluating behavioral and physiological responses to the procedure, including changes in cortisol, β-endorphins, vocalizations, and pain-related behavioral endpoints [ 1 , 25 ]. Although there are well over fifty publications that evaluate castration pain in pigs, no studies to date have validated these endpoint measurements used to quantify castration pain [ 1 , 2 , 34 ]. When recommending pharmaceutical intervention for pain, the lack of validated measures, combined with poor-quality evidence demonstrating drug efficacy, has prevented the development of nationally accepted industry guidelines for pain management [ 2 ].…”