Lou, M. E., Kleinhenz, M. D., Schroeder, R. et al. 2022. Evaluating the utility of a CO2 surgical laser for piglet tail docking to reduce behavioral and physiological indicators of pain and to improve wound healing: A pilot study. Applied Animal Behaviour Science 254, 105720.

In the U.S. millions of commercially raised piglets are routinely tail docked. Human and veterinary medical patients experienced reduced inflammation, healing time and post-procedural pain using a CO2 surgical laser compared to standard surgical instruments. Refinement of the tail docking procedure using a laser may improve piglet welfare by reducing tail docking-associated pain compared to cutting pliers. The objectives of this pilot study were to evaluate the ability of a CO2 surgical laser to 1) reduce pain and 2) improve wound healing of piglets after tail docking. Thirty piglets (male and female; 2 days old) were randomly allocated to one of three treatments (n = 10 piglets/treatment): tail docking with side pliers (SP), tail docking with a CO2 surgical laser (LA) or sham-tail docking (control; CON). Piglet vocalizations were recorded during the tail docking procedure and the maximum frequency, amplitude and energy were quantified. Piglet behavior was recorded for 30 min at baseline and at 0, 1, 2, 6, 7, 8, and 24 h post-procedure. Facial images were collected at the same time points to assess facial grimacing using the Piglet Grimace Scale (PGS). Digital images of the tail tip were taken at baseline and up to 168 h post-procedure for wound healing assessment. Infrared thermography (IRT) images of the tail tip and its surrounding tissues were taken at baseline, 0, 0.5, 8, and 24 h post-procedure to assess inflammation. Blood samples were collected from each piglet at baseline and 0.5 h and saliva samples at baseline, 0.5 and 8 h post-procedure for cortisol analysis. The LA and CON groups elicited calls of higher energy than the SP group (P < 0.0001). Across the assessment period, the SP group had higher grimace scores than the LA group (P = 0.03). Additionally, male piglets grimaced more than female piglets (P = 0.009). A treatment effect was observed for both wound scores and IRT (P < 0.0001). At 0 h the SP group had significantly higher wound scores than the LA and CON group (P < 0.0001). At 0 h, the SP group had a greater temperature difference between the tail tip and surrounding tissue compared to the LA group (P = 0.02). Behavioral indicators of pain were not different between the SP and LA piglets. In conclusion, LA piglets had less tail damage immediately post-procedure and lower facial grimace scores throughout the assessment period, suggesting it may have the utility as a less painful alternative to traditional tail docking with cutting pliers in piglets.

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