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Beyond the Bale : March 2019
ON FARM 41 TAIL DOCKING DON’T CUT IT SHORT Tail docking is a standard practice in the sheep industry and is important in helping reduce susceptibility to flystrike, but care must be taken to do it correctly. Veterinarian and sheep researcher Dr Joan Lloyd says the length of the docked tail is of prime importance and has life-long implications for the individual sheep’s health. “A shorter tail may be considered to be ‘cleaner’ and ‘neater’ but in fact a longer tail is far better for the sheep in many ways,” Dr Lloyd said. “Tails cut long (four knuckles) or medium-long (three knuckles) are associated with better outcomes for the sheep across a number of different considerations.” Extensive research on appropriate sheep tail length was done in Australia in the 1930s and 1940s and Dr Lloyd said the findings are still highly relevant but unfortunately not always followed. “This early research included approximately 10,000 unmulesed Merinos and Corriedales, and included ewes and wethers,” Dr Lloyd said. “It concluded that tails docked either medium-long (three knuckles) or long (four knuckles) gave better protection against breech flystrike than did shorter tails. The medium-long and long tails also healed faster and were less likely to become infected.” Dr Lloyd said one reason why shorter tails are less effective at preventing breech flystrike is because the sheep cannot adequately move the tail. “Short docking cuts through the muscles at the base of the tail, so the sheep can no longer lift or twitch it normally. It cannot raise its tail when it defecates and cannot flick flies away. “Cutting through these muscles also prevent the proper functioning of the muscles that encircle the anus, which predisposes sheep to rectal prolapse. A good landmark to ensure you don’t cut through these muscles is the bare area on the underside of the tail. If this bare area remains intact, then the muscles at the base of the tail will continue to function normally.” Further research on sheep tail length conducted by Dr Lloyd in 2014-15 (funded by MLA) identified an association between tail length and bacterial arthritis and polyarthritis in lambs. Again, longer tails gave better outcomes. “We found shorter tails (one or two knuckles) have a higher risk factor for arthritis and polyarthritis than longer tails (three or more knuckles),” Dr Lloyd said. “The most common cause of bacterial joint infections in Australian lambs is Erysipelothrix rhusiopathiae, which usually causes a fibrinopurulent arthritis and osteomyelitis after docking or castration.” These arthritic conditions are characterised by swelling, inflammation and pus. Vaccines to prevent Erysipelothrix infection are available from veterinarians. Dr Lloyd said good hygiene and tail docking practices that promote rapid healing should be followed. “The younger the lamb and the longer the tail is left, the quicker the tail docking wound heals,” she said. Research has also identified an association between short tail docking and cancer of the perineal region. This is related to the increased sun exposure on the delicate perineal tissue in sheep with short tails “The long and the short of it is that shorter tails are a factor in many negative outcomes for sheep with no positive benefits. As such there is no reason to dock tails short. Docking at the fourth knuckle is the best option,” Dr Lloyd said. “Tail docking is an important operation. It is a surgical procedure. Only well-trained, careful workers should be allowed to do it and pain relief should be provided to the lambs. “Ideally, pain relief should be applied to the tail. There are highly effective formulations of local anaesthetic now registered for use in tail docking in Australia. Ideally, the ‘gold standard’ of pain relief would involve a local anaesthetic and a longer acting analgesic used together – something to numb the site while the surgery is performed and something for the residual pain after the procedure. But at a minimum, at least one or the other should be given. “Where the ring or hot knife blade is placed on the lamb’s tail at marking will determine the tail that the sheep carries through life,” Dr Lloyd said. “It’s worth taking a moment to get it right. For the very best outcome, count the knuckles down from the base of the tail, put the ring or cut below the fourth palpable joint.” In a 2017 AWI survey of 1,200 woolgrowers on their Merino husbandry practices, 53% reported that they were docking their sheep at the 3rd or 4th joint (see below). Along with the increased risk of arthritis, there are many local factors that can influence woolgrowers’ decisions on tail length such as the large regional environmental variations in risks from sun cancers and dags. There is no reason to dock tails short. Tails cut long (four knuckles) or medium long (three knuckles) are associated with better outcomes for the sheep. Docking at the fourth knuckle is the best option. 50% 45% 40% 35% 30% 35% 20% 15% 10% 5% 0% 1 Joint 2 Joints 3 Joints 4 Joints Length that tails are docked Percentageofgrowers(national) Tail docking length of ewe lambs survey (AWI 2017)
In the Shops - March 2019