Wound healing after mulesing and other options for controlling breech flystrike in Merino lambs: quantitative and semiquantitative analysis of wound healing and wound bed contraction.

Abstract

BACKGROUND: A two-part study examined wound healing and contraction occurring after mulesing and two alternative methods of preventing breech flystrike in sheep. OBJECTIVE: To quantify wound healing using a scoring system and to assess the contractility of the wound bed of the breech after mulesing, cetrimide-intradermal treatment and application of clips. METHOD: The study group of 30 mulesed, 30 cetrimide-intradermal treated, 30 control and 10 clip-treated sheep were humanely killed at six time points from 3 to 47 days after each treatment. Wound healing post treatment was assessed using a scoring system, and contractility was assessed by the quantification of myofibroblast expression. Statistical analyses allowed comparisons of temporal wound healing and contraction between treatment groups. RESULTS: Mulesing wounds healed faster in the first 11 days, but by 19 days wound healing was similar between the mulesing and cetrimide-intradermal groups. By 32 days, all three treatment groups had similar wound healing scores. There was greater myofibroblast expression in the mulesing group in the first 11 days after treatment, but by 19 days expression was similar in both the mulesing and cetrimide-intradermal groups. The clip group had significantly less myofibroblast expression from 32 days after treatment. CONCLUSION: Wound healing is initially most rapid after mulesing, but there are similar wound healing scores in the mulesing and cetrimide-intradermal treatment groups by 19 days. Both mulesing and the cetrimide-intradermal treatment induce a similar amount of wound bed contraction, with less contraction observed after application of clips.