205. Tail Docking by Hot-iron Cauterization: Healing Progression of Lambs Docked at Birth or Five Weeks of Age.

Abstract

Tail docking using a heated cautery iron is a common husbandry practice on sheep farms and is typically performed within the first two months of life. However, little is known about wound healing following cautery docking, an important consideration for animal welfare. Our objectives were to characterize wound healing in lambs docked near birth and compare early wound healing in lambs docked near birth versus five weeks of age. We used 30 Polypay (Ovis aries) lamb twin pairs, with one lamb per pair docked at 1–2 days (n = 30) and the other at 34–36 days (n = 30). Tail wounds were photographed weekly until weaning (mean ± SD: 67 ± 6 days) and scored for the presence or absence of external tissue and fluid types. Wounds were considered healed when none of these features were present. Of the 30 lambs docked at birth, 25 fully healed by weaning; 2 died prior to weaning and 3 did not fully heal within the observation period. Among the 25 lambs that fully healed, wounds took 38 ± 9 days to heal (mean ± SD). Crust was the most prevalent tissue (present on 49.5 ± 18.9% of observation weeks per lamb) followed by granulation (38.1 ± 20.7%), serous exudate (16.2 ± 16.1%), sanguineous exudate (13.7 ± 9.0%), purulent exudate (10.5 ± 11.7%), and slough (9.4 ± 15.4%). Purulent exudate, a sign of infection, was present at least once in 60.7% of wounds. The number of days purulent exudate was present was associated with delayed healing; each additional day reduced the instantaneous rate of healing by 56% (HR = 0.439, P = 0.005). No other tissues were significantly associated with healing time. A mixed binomial regression model revealed no significant effect of docking age (birth vs 5 weeks), week post-docking (first or second), or their interaction on the presence of serous exudate, granulation, or purulent exudate. Crust was excluded from model analysis because it was present in all individuals across the first two weeks, and slough occurred too rarely for reliable modeling and was summarized descriptively. Sanguineous exudate decreased significantly from the first to the second week post-docking (p = 0.023) and was observed nearly twice as often in 5-week docked lambs (26.7%, 16 out of 60 observations) compared to lambs docked at birth (14.3%, 8 out of 56 observations). These results suggest similar early healing trajectories regardless of docking age, though greater sanguineous exudate in lambs docked at five weeks may reflect increased tissue damage from a larger wound. Future research should compare the entire healing trajectory across docking ages. The high prevalence of infection in lambs docked near birth raises important welfare concerns and highlights the need for improving docking management and aftercare.