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Data from: Wound characteristics after disbudding: Part I and part II

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Aug 04, 2025 version files 5.66 MB

Abstract

Part I: Disbudding is a common painful procedure in dairy calves. Farms vary in method (hot iron or paste), whether horn bud hair is shaved, or the quantity of paste applied, for example. Yet, little research compares the effects of differing paste applications. Our objective was to assess the effects of dose and shaving horn bud hair on caustic paste disbudding outcomes including disturbance from rubbing, wound size, sensitivity, healing time, horn regrowth, and the need for removal with a 2nd procedure. Female Holstein calves were assigned to 1 of 4 caustic paste treatments (n = 24-25/treatment): 0.2 or 0.3 mL on either shaved or unshaved horn buds, respectively (0.2 Unshaved, 0.2 Shaved, 0.3 Unshaved, 0.3 Shaved). Before disbudding at 3 d of age, calves received a local block and systemic pain relief. Wound tissues and regrowth were scored 1-2x/wk until fully healed. Wound depth, diameter, and mechanical nociceptive thresholds (MNT) to evaluate sensitivity were measured approximately 4, 14, 28, 42, 56, and 70 d after disbudding. Calves with shaved horn buds were more likely to disturb their paste by rubbing it on themselves or their housing up to 4 h after application. This risk was lowest with 0.2 Unshaved (12%) and highest with 0.2 Shaved and 0.3 Shaved (both 58%). Rubbing, which may result from irritation when the local anesthetic wears off, had minimal effects on wound outcomes. Wound depth initially increased by ~1.5 mm for all treatments in the 6 wk after paste application. Similar sensitivity was observed for all wounds for 42 d, while at 56 and 70 d, 0.2 Shaved calves were less responsive than 0.3 Shaved. Wound diameter was affected by dose and shaving with 0.2 Unshaved wounds being an average 6 mm smaller than those from 0.3 Shaved. On average, wounds from 4 methods of applying caustic paste took 14.3 to 18.0 wk to re-epithelialize and 15.9 to 19.4 wk to fully heal, with 0.2 Unshaved reaching these stages the fastest and 0.3 Shaved the slowest. Applying 0.2 Unshaved led to smaller, faster healing wounds, but also resulted in the highest rates of horn regrowth (21% regrowth present; 8% required 2nd procedure), indicating this approach to paste disbudding was the least effective option tested. At the other extreme, 0.3 Shaved caused the most rubbing initially, and long term, created wider, slower healing wounds, beyond what is needed for a successful procedure. Two treatments, 0.2 Shaved and 0.3 Unshaved created comparable, long-lasting damage in our population of limit fed calves. While these 2 approaches were the best of the 4 compared, they take on average 4.4 mo to heal, raising concerns about the ethical implications of using chemicals to destroy horn growing tissue. Overall, the dose of disbudding paste and presence of hair affected calf responses, the wound profile, and efficacy of the procedure.

Part II: Disbudding is a common painful procedure. Farms vary in method (cautery or paste), whether the horn bud hair is shaved, or the quantity of paste applied, for example. Yet, little research compares the long-term effects among these methods. Our objective was to describe wound healing, sensitivity, and horn regrowth following cautery and 2 methods of caustic paste disbudding. Female Holstein calves were assigned to 1 of 4 treatments (n = 25/treatment): non-disbudded sham (Control), 12.7 mm hot iron leaving the bud in (Hot iron), 0.2 mL paste on shaved horn buds (0.2 Shaved), or 0.3 mL paste on unshaved horn buds (0.3 Unshaved). Before disbudding, at 3 d of age, calves received a local block and systemic pain relief. Wounds were scored 1-2x/wk until they were fully healed and only a thin scar line remained. Nine tissue types were scored, including epithelium, when the wounds were covered in a new layer of skin. Wound depth, diameter and mechanical nociceptive threshold (MNT) measures to evaluate sensitivity were collected 4, 14, 28, and 42 d after disbudding. Compared to Controls, all disbudded calves exhibited lower MNT values in the first 42 d, while sensitivity was similar among disbudding treatments. Wound diameter was similar 4 d after disbudding. In the following weeks wounds from Hot iron contracted while those from paste first increased in size. Wound depth in the weeks after disbudding was smaller for Hot-iron disbudding than paste. Paste wounds took 16 and 17-18 wk to epithelialize and heal, respectively and this was at least twice as long as Hot Iron, where these stages were reached after 7 and 10 wk, on average. Horn regrowth was present in 4% of buds from both Hot iron and 0.3 Unshaved, and 8% from 0.2 Shaved. Applying 0.2 Shaved or 0.3 Unshaved paste created similar wound size, sensitivity, healing, and regrowth, confirming the likeness of these ways of chemically destroying horn growing tissue. Taken together, all wounds were more sensitive than un-damaged tissue for at least 42 d, and paste wounds were deeper and increased in size while Hot-iron wounds contracted. Paste wounds also took at least twice as long to re-epithelize and fully heal compared to those from cautery disbudding. These results highlight the importance of understanding methodological differences associated with routine management procedures and suggest cautery disbudding is better for calf welfare than caustic paste.