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Beyond the Bale : Jun - Jul 08 Supplement
byrobintaylor R esearch on an intradermal injection as an alternative to mulesing has taken another important step with further trials of the intradermal compound beginning in New South Wales. Known as Skintraction™, the product has been developed by Cobbett Technologies Pty Ltd, a private Sydney-based research and development company. Cobbett Technologies R&D director, and former CSIRO scientist, Peter St Vincent Welch, says they are aiming to register the product in 2009-10. Skintraction™ uses sodium lauryl sulphate (SLS) as its active ingredient, a chemical widely used in shampoos, cleaning products and the pharmaceutical industry. Four years ago, Mr St Vincent Welch – one of the pioneers of biological wool harvesting – decided to go back to basics in the search for an injectable mulesing alternative. “I decided to look for a chemical which was available in the pharmaceutical industry – it had to be widely used and have the characteristics we needed,” he says. From his research into products that cause necrosis of the skin, he began looking at sclerosing agents, widely used in the treatment of varicose veins. Trials with the best of these compounds, sodium tetradecal sulphate (STS) gave good responses, with no adverse reactions from animals. The problem was the cost of the product using STS. So, Mr St Vincent Welch turned his attention to closely related compounds with a similar response. SLS is a widely used compound, with extensive information available on its toxicology, residues, and environmental impacts. When used on sheep it gave the same response as STS, with very little stress to the animal. When SLS is injected into the skin, the chemical denatures protein in the skin, including the pain sensing fibres, blood vessels and the protein structures integral to skin structure. Destruction of the pain-sensing systems in the skin results in the treated region being effectively anaesthetised and the animal feeling minimal pain. “The literature indicates that 90 per cent of the chemical is excreted within eight hours of injection,” Mr St Vincent Welch says. Within minutes of application, there are obvious signs that the skin has been damaged. After six days the treated skin has hardened and thickened forming an eschar (dry scab). The surrounding tissues then contract underneath the eschar, to give the same stretching effect as in a mulesed animal, but without an open wound. To deliver the chemical, Mr St Vincent Welch has modified a needleless injector to include a number of small-diameter, blunt hypodermic needles. These needles, surrounded by a shroud, go through the fleece to the skin surface. The gun is designed so that when the operator pulls the trigger and presses it against the skin, chemical under pressure is injected into the skin. The injector can be refired after 1.5 seconds. With a grant from AWI, Cobbett Technologies is commencing field trials to fine- tune the operation of the injector. Trials have shown that lambs and weaners react differently – lamb skin can reconstitute itself more readily than weaner skin, so dose rates need to be adjusted to ensure this does not occur. The field trials to fine-tune the applicator are being carried out in NSW. Mr St Vincent Welch is optimistic that they will be completed within six months so that commercial trials can begin in 2009. AWI is supporting Skintraction™ and has discontinued research into other intradermal options. ú theskintraction™needlelessapplicatordeliversameasureddoseofformulationintradermally. 14 beyondthebale roadto2010supplement MulesinG alternatives intradermal research hones in on new compound needleless injection of sodium lauryl sulphate is giving good results in trials, and work is continuing to fine-tune both the compound and its application pho to: Cobbett t eC hnolo GI es
Apr - May 08
Jun - July 08