Wound healing after mulesing and other options for controlling breech flystrike in Merino lambs: observations on gross and microscopic wound healing.

Abstract

BACKGROUND: The mulesing procedure is the main procedure used to control breech flystrike of sheep in Australia, but other permanent methods of altering breech conformation are currently being investigated and wound healing is an important component of that comparative assessment. OBJECTIVE: To qualitatively assess the gross and microscopic tissue damage and wound healing that occurs in the immediate post-treatment period after mulesing, intradermal-cetrimide treatment and clip application. METHOD: The study group of 30 mulesed, 30 cetrimide-treated, 30 control and 10 clip-treated sheep were humanely killed at six time points during the 3-47 days post treatment. Treatment sites and wound beds were examined grossly and microscopically. RESULTS: Mulesing wounds healed rapidly in a predictable manner, producing long linear scars on either side of the breech and tail by 32-47 days post treatment. Although the time course for healing post cetrimide-treatment was similar to that for mulesing, complications occurred and included inadequate wound healing because of persistence of adherent necrotic tissue, poor skin tightening around the tail, and patchy or deep penetration of the cetrimide resulting in necrosis of adjacent skin and deeper structures. The clips resulted in skin tightening around the ventrolateral breech and tail, although the formation of skin tags and clip slippage were of concern in some sheep. CONCLUSION: Wounds healed rapidly after mulesing with minimal complications. The intradermal-cetrimide treatment appeared to produce imperfect and sometimes delayed wound healing compared with mulesing. The clips resulted in comparable wound healing to mulesing, but further field trials are required to assess their effectiveness in flystrike prevention.