48. Effects of Pain Control Methods, Including a Lidocaine-impregnated Elastrator Band, on Growth Performance and Wound Healing in Lambs.

Abstract The objective of this study was to evaluate the effects of tail docking pain control on wound healing and growth performance in lambs. We hypothesized that increasing pain control across treatments would improve these outcomes. Seventy-one lambs (40 male, 31 female; Rideau-Arcott x Dorset) were enrolled at birth at the University of Guelph's Ridgetown Sheep Research Centre. Lambs were randomly assigned to one of four treatments, balanced for birth weight, sex and litter size: 1) no pain control (n = 19), 2) local anesthetic (SQ lidocaine at docking site) and analgesia (meloxicam) (n = 18), 3) local anesthetic only (n = 17), or 4) a lidocaine-impregnated elastrator band (LidobandTM; n = 17). Tail docking was performed at 24-48 hours of age using a rubber elastrator ring (groups 1, 2, 3) or LidobandTM (group 4). Wound healing included wound and swelling scores (1-4 severity scale; 4 = most severe), time to tail detachment, and time for complete wound healing, each assessed weekly. Lambs were weighed weekly to determine average daily gains (ADG). Tail diameter (mm) and wool depth (mm) were measured before docking. Data was analysed in SAS Studio using logistic regression and generalized linear mixed models with lamb as the experimental unit and week as a repeated measure for ADG and weight models. ADG tended to differ between treatments (P = 0.09), with lambs that did not receive pain control having lower growth rates than lambs receiving anesthetic and/or analgesia; means (± SE) of 0.30±0.02, 0.35±0.02, 0.34±0.02, and 0.35±0.02 kg/day for treatments 1-4, respectively. Body weight differed between treatments (P = 0.04) with a treatment by time interaction (P < 0.01). Lambs began at similar weights but differed by 14 weeks, with mean weights (± SE) of 35.1±1.05, 37.6±1.05, 39.0±1.09, and 39.4±1.06 kg for treatments 1-4, respectively. Maximum swelling score tended to be associated with wool depth at the docking site, where increasing wool depth increased the odds of a maximum swelling score of > 3 (OR = 1.13; P = 0.07); but showed no association with treatment, sex, or tail diameter. Maximum wound score of > 2 was not associated with treatment, sex, tail diameter, or wool depth. Time to tail detachment and healing was 2.50 (range: 2-4) and 5.44 (4-8) weeks, respectively. Healing time was associated with tail diameter at enrollment, increasing by 0.17 weeks for each 1 mm increase in diameter (P = 0.01). Neither time to detachment nor healing was associated with treatment, sex, wound or swelling scores. These results suggest that pain control during tail docking may improve lamb growth performance, however wound healing and swelling outcomes did not appear to be affected by treatment.