With or without antimicrobial spray: a clinical field trial on wound healing after disbudding of dairy calves

Hannes Bijkerk ^* Mirjam Nielen Ingeborg Marianne Van Geijlswijk Hans Vernooij Ruurd Jorritsma

• Utrecht University, Utrecht, Netherlands

Calves are routinely disbudded with hot iron disbudders in the Netherlands. Disbudding wounds are frequently treated with antimicrobial wound spray with the aim to prevent infection and improve wound healing. Given the policy for prudent use of antimicrobials, we decided to evaluate the effect of antimicrobial wound spray versus non-antimicrobial wound spray after disbudding in a commercial setting. In this field trial, we treated 255 calves after disbudding with Chlortetracycline spray (CTC) and Keno™Fix (KF) on alternating the left and right horn buds. At 1 week and 4 weeks after disbudding, we measured the healing rate in mm/week (HR) and the lesion score (LS) of the wounds. The field conditions on farms were also monitored and investigated for an effect on HR and LS. The HR of KF wounds was numerically lower than CTC wounds but did not pass the non-inferiority threshold of 0.5 mm/week. Lesion scores were worse for KF treated wounds compared to CTC treated wounds. For both CTC and KF wounds, we found that a worse lesion score was associated with a lower HR. We found that lesion scores were worse for KF treated wounds and calculated that it is necessary to treat 5 calves with CTC to prevent 1 calf from developing an inferior wound score. As the HR of KF was lower, but not inferior to CTC treated wounds, we conclude that in certain circumstances it is not needed to use a spray with antibiotics after cautery disbudding of calves.