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.

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.

Assessment of the short-term systemic effect of and acute phase response to mulesing and other options for controlling breech flystrike in Merino lambs.

BACKGROUND: Mulesing is an important method of preventing flystrike of Merino sheep in Australia, but because there are important short-term welfare issues associated with mulesing, alternative methods of removing the skin folds for breech flystrike prevention are being investigated. OBJECTIVE: To examine the short-term systemic effects of mulesing and two proposed alternatives, compared with two control methods, for controlling breech flystrike. METHOD: The five treatment groups comprised 10 lambs each: (1) mulesing, (2) intradermal-cetrimide treatment, (3) clip application, (4) tail docking only and (5) no treatment. Changes in body weight, haematological and biochemical profiles, and concentrations of fibrinogen, haptoglobin and serum amyloid A were measured repeatedly for 29 days post treatment. RESULTS: The mulesing and intradermal-cetrimide groups were the only treatment groups to lose weight during the first week, with greater weight loss in the mulesing group. The mulesing group had the most marked increases in all three acute-phase protein concentrations, closely followed by the intradermal-cetrimide group, with a mild increase observed for the clip group and even less for the tail-docked group. The mulesing group was the only group to develop mild anaemia, transient hyperglycaemia and a persistent decreased albumin : globulin ratio. The neutrophil : lymphocyte ratio was above the upper reference limit for both the mulesing and intradermal-cetrimide groups. CONCLUSION: Mulesing had the greatest systemic effect in terms of the magnitude and duration of increased acute-phase protein concentrations and haematological, biochemical and body weight changes. The clips had a significantly reduced systemic effect compared with mulesing, with the intradermal-cetrimide treatment in between the two. Tail docking had a minimal systemic effect.

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

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.

Haematological, biochemical and selected acute phase protein reference intervals for weaned female Merino lambs.

BACKGROUND: Merino lambs are currently the subject of much research into the welfare aspects of mulesing and mulesing alternatives. OBJECTIVE: Obtain haematology, biochemistry and acute phase protein reference intervals using modern methodologies for female Merino lambs. METHOD: Blood was collected from 50, weaned, 9- to 16-week-old, female Merino lambs. Haematology and biochemistry panels were performed using routine automated methods. The acute phase proteins, fibrinogen, serum amyloid A and haptoglobin, were also measured using commercially available techniques. The reference intervals were determined to be the central 95% of results. RESULTS: Differences in the concentrations for some analytes were seen when compared with reported studies in sheep, but may be explained by the use of sheep of a different signalment, as well as different methodologies for analyte measurement. Overall, most analytes gave similar values to those previously reported in other studies. Notable exceptions were alkaline phosphatase, phosphate and globulins, for which the different results were often attributed to the younger age of the sheep in the present study, and platelets and creatine kinase, for which the elevated levels may have been a result of stress and muscle exertion associated with blood collection and husbandry practices. CONCLUSION: Established haematological, biochemical and acute phase protein reference intervals are necessary for the investigation of the systemic impact of mulesing and mulesing alternatives and for the investigation of systemic diseases affecting weaned, 9- to 16-week-old, female Merino lambs in general.