Effectiveness of a non-surgical alternative to the Mules operation in sheep

Objective To measure changes to the perineal bare area, local tissue reaction and healing responses of young sheep, following intradermal administration of cetrimide and polyvinylpyrrolidone (PVP), with and without ethanol, to the breech and tail. Method A needle‐less injector was used to deposit formulations containing 40 g/L cetrimide and 30 g/L PVP (group 2) or 20 g/L cetrimide, 30 g/L PVP and 15 g/L ethanol (group 3), within the dermis of the tail and the region surrounding the perineal bare breech area of groups (N = 8) of Merino weaner sheep. The dimensions of the perineal bare area (length, width and diagonal distances left and right) and tail width were recorded before and at intervals after treatment for 60 days. Observations of swelling and bruising and scab formation at the treatment sites were recorded for up to 35 days after treatment. Rectal temperatures were monitored for up to 35 days after treatment and bodyweight for up to 60 days after treatment. An untreated control group (group 1) was included. Results Comparison of day ‐3 and day 35 measurement data showed that both treated groups had significantly (P < 0.05) wider breech bare areas compared to the untreated controls and that group 2 sheep had significantly (P < 0.05) longer breech bare areas compared to group 3 sheep or to the untreated controls, which were not significantly different. At this time scabs were still firmly in place on many treated sheep. At day 35 there was no increase in tail bare area caused by either treatment. By day 60 there was no significant difference between the treated and control groups in either the breech or tail regions indicating that the changes present at day 35, were not permanent. Mean weight gain in the groups throughout the 60‐day interval was unaffected by treatment. Intradermal treatment was associated with a significant elevation in body temperature. This effect lasted for 3 days and was associated with signs of discomfort and depressed appearance in at least some of the treated sheep. Bruising was mild to severe in all treated sheep within two days of treatment but was not evident in any sheep by day 21. Mild to moderate swelling was also associated with treatment but was not uniform across sheep in the groups. The tail of one sheep was severely swollen for several days. Swelling remained obvious in most treated sheep until day 14 but was not present at day 21. Conclusion Under the conditions of this study intradermal injection of cetrimide had no permanent effect on bare area measurements on the breech or the amount of wool‐bearing skin on the tail. It also caused signs of discomfort and pain that raise welfare concerns.     

Physiological and behavioural effects of intradermal injection of sodium lauryl sulfate as an alternative to mulesing in lambs

Objective To assess the effects on physiology and behaviour of intradermal injection of sodium lauryl sulfate (SLS) as an alternative to mulesing. Procedures Three groups of Merino lambs were studied: Control (n = 10), SLS (n = 11) and Mulesed (n = 11). The SLS group received SLS (7% w/v) and benzyl alcohol (20 mg/mL) in phosphate buffer, and the Mulesed group received 6 mL topical local anaesthetic as a wound dressing. Haematology, cortisol, beta-endorphin and haptoglobin concentrations, rectal temperatures, body weight and behaviours were monitored for up to 42 days post treatments. Results SLS treatment induced mild swelling followed by thin scab formation. Fever (>40°C) was observed at 12 and 24 h, cortisol concentration was elevated on days 1 and 2, haptoglobin concentration was highly elevated on days 2–7, white blood cell count was elevated on days 2 and 4 post treatment, but average daily gain was not affected. Fever at 12 h was significantly higher in the SLS than in the Mulesed group, whereas maximum temperature, temperature area under the curve (AUC), occurrence of fever, cortisol profile, cortisol AUC, white blood cell counts and haptoglobin concentrations until day 7 were comparable. The behaviours of normal standing, total standing and total lying were modified for 2 days by SLS treatment, but changes were less marked and of shorter duration than in the Mulesed group. On day 1, the SLS group spent <5% of time in total abnormal behaviours compared with 18% in the Mulesed group. The SLS group tended to spend more time in abnormal behaviours on day 1 than the Controls. Conclusions The behaviour of the SLS group was similar to that of the unmulesed Controls and their physiological responses were intermediate between the Mulesed lambs receiving post-surgical analgesia and the Controls.     

Prevalence of breech-strike in mulesed, clipped and unmulesed Merino hoggets in south-eastern Australia

Objective To compare the prevalence of breech flystrike (‘breech‐strike’) on 12–20‐month‐old Merino hoggets that were mulesed, had breech and tail clips applied (‘clipped’) or were left unmulesed but treated strategically with long‐acting insecticide. Design A cohort study on three farms in southern Victoria. Methods Three treatment groups were established at lamb marking on each farm. The unmulesed group was treated with dicyclanil when 12 months old in September or October (‘early‐season treatment’). The prevalence of breech‐strike and key risk factors, including soiling of the breech with faeces (‘dag’) and urine (‘stain’), and breech wrinkle, were compared between the groups. Results Over all the farms, breech‐strike occurred on 1.1% of mulesed sheep and 7.7% of clipped sheep. Clipped sheep had a relative risk of breech‐strike of 18.2‐, 16.8‐ and 3.0‐fold that of mulesed sheep on the three farms. Unmulesed sheep treated with dicyclanil had a similar prevalence of breech‐strike to that of mulesed sheep (overall 0.9%, range 0–2.5%), but had significantly more dag, stain and wrinkle. Conclusion Early‐season treatment of unmulesed sheep prevented most breech‐strikes during the spring and early summer, and offers a short‐ to medium‐term option for the control of breech‐strike in south‐eastern Australia. There were some benefits associated with using clips, namely less dag and stain, and a shorter time spent crutching. However, to control breech‐strike the clipped sheep should be treated the same as unmulesed sheep. Reducing the prevalence and severity of dag will be a major component of strategies to control breech‐strike of Merinos in this region.     

Effects of meloxicam or tolfenamic acid administration on the pain and stress responses of Merino lambs to mulesing

OBJECTIVE: To determine the effectiveness of two long-acting non-steroidal anti-inflammatory drugs (NSAIDs) at reducing the pain and stress responses to mulesing in lambs. PROCEDURES: Merino lambs (n = 60) were allocated at 5 weeks of age to six treatment groups: (1) sham mules; (2) mules; (3) tolfenamic acid-sham mules; (4) tolfenamic acid administered 45 min before mulesing; (5) tolfenamic acid at the time of mulesing; (6) meloxicam at the time of mulesing. Plasma cortisol was measured at -0.75, -0.25, 0, 0.5, 1, 3, 6, 12, 24, 48 and 72 h relative to mulesing. Beta-endorphin concentrations in plasma were determined at 0, 0.5, 1, 6, 12, 24, and 48 h. Haematology was performed on blood samples taken at -0.75, 0, 24, 48 and 72 h. Plasma haptoglobin was measured at 0, 12, 24, 48 and 72 h. Rate of wound healing was determined 72 h post mulesing, and animal behaviour, including posture, was measured for 6 h after mulesing. RESULTS: The mulesed lambs exhibited large increases in plasma concentrations of cortisol, beta-endorphin and haptoglobin. All mulesed animals lost weight significantly in the week after mulesing, regardless of analgesic administration, but the difference in weight between mulesed and unmulesed lambs was less at the final measurement, 2 weeks after mulesing. Mulesed lambs spent significantly less time lying ventrally than control lambs. All lambs that were mulesed, including those administered NSAIDs, spent more time standing with a hunched posture and less time walking normally than control lambs. CONCLUSIONS: The NSAID treatments applied 45 min before or at the time of mulesing at the dose levels used in this study were not effective in reducing the acute response of lambs to mulesing.