Sensitivity and wound healing after hot-iron disbudding in goat kids

Abstract

Hot-iron disbudding in goat kids causes acute pain and tissue damage. However, the duration of healing and wound sensitivity is unknown. We assessed wound healing and pain sensitivity in 18 female dairy goat kids disbudded with a heated iron at 10 d of age (range: 5-15 d). Pressure algometry was carried out twice a week from d 1 after disbudding to determine the mechanical nociceptive threshold (MNT) in 4 locations on each bud (front, lateral, caudal, and middle). At the same time, digital and infrared images of the wounds were used to visually and thermally describe the healing process. Wounds were visually scored daily for the presence of 7 tissue types: attached necrotic tissue, detached necrotic tissue, burns outside the necrotic ring, exudate, granulation, crust, and epithelium. All data were taken until epithelium was present for 4 consecutive days. Necrotic tissue detached completely from the scalp 26 ± 5 d after the procedure (mean ± SD; range: 17-43 d), and wounds took 50 ± 8 d (35-63 d) to re-epithelialize. Wounds were more sensitive at all stages of the healing process compared with re-epithelialized tissue. The caudal and middle locations were the most-and leastsensitive test sites (1.24 ± 0.10 and 1.90 ± 0.10 N, respectively; mean ± SE). Goats became less responsive to stimulation as their wounds decreased in size. Sensitivity did not differ between left and right sides of the head. Maximum surface temperature of necrotic tissue, when present, tended to be higher than that of epithelium (38.8 ± 0.2 vs. 38.1 ± 0.2°C); temperature did not differ among other tissue types. Our results indicate that hot-iron disbudding wounds in goats take, on average 7, wk to re-epithelialize (35-63 d) and are painful throughout this time, raising additional welfare concerns about this procedure.

Iron and laterality effects on healing of cautery disbudding wounds in dairy calves

“…No effect of side on the presence of other tissue types or latency to re-epithelialize was observed. Side did not affect wound size (left: 14.0 ± 0.4 mm; right: 13.8 ± 0.5 mm; F 1,416 = 0.39; P = 0.535), nor did it affect wound temperature (Alvarez et al, 2019). For latency to re-epithelialize, we observed more variation between than within subjects (58 vs. 42%).…”

“…Because the Portasol has a larger tip circumference, the resulting wounds tended to be larger in diameter than those from the Rhinehart for the first 2 wk after disbudding. By wk 4, the pattern reversed, such that Rhinehart wounds were larger 1 Experiment A (current study), 10 calves; experiment B (Adcock and Tucker, 2018), 24 calves; experiment C (Alvarez et al, 2019), 18 goat kids. Tissues were scored daily in experiments A and C, and twice weekly in experiment B until the wound had re-epithelialized.…”

“…Wounds were highly variable in how long they took to re-epithelialize: some took 5.7 wk, and others up to 10 wk. Adcock and Tucker (2018) and Alvarez et al (2019) also reported substantial ranges in wound healing times for experiment B (6-13 wk) and C (5-9 wk), respectively. In addition to horn-bud-level factors discussed previously, between-individual differences in energy status, immune function, chronic stress, and wound-directed behaviors, among other factors, likely contribute to this variation.…”

“…Experiment C. Eighteen female dairy kids were disbudded at 10 d of age (Alvarez et al, 2019). Briefly, a heated iron (Rhinehart X30; 501 ± 30°C) was applied to each horn bud for 10 ± 2 s. No pain relief was provided, following the farm's standard operating procedure.…”

Characterization of Efficacy and Animal Safety across Four Caprine Disbudding Methodologies

“…Still, the procedure is painful as evidenced by both an increase in cortisol and pain behaviors after disbudding [2][3][4]. Furthermore, there is risk of thermal injury to the brain [5,6], the healing lesions are susceptible to infection [7], and remain more sensitive to nociceptive pressure until re-epithelialization, which can take 5-9 weeks to occur [8]. Although adjunct anesthesia and analgesia can reduce acute pain associated with hot iron disbudding [9][10][11], chronic pain is more challenging to address in production settings and it is important to look beyond acute pain when assessing welfare.…”