Sheep Medicine Q&A 08

This question was provided by Manson Publishing as part of the OVAL Project. See more Sheep questions

In late summer a farmer complains that some ewes have lost considerable condition as a consequence of not grazing and are observed frequently kicking at their heads with their hindfeet, causing serious damage to the poll and ears. The affected ewes seem distressed, frequently running 10–15 m then stopping, only to start running away again.

Question	Answer		Article
What are possible causes of this problem? (Most likely cause first.)	Feeding around head wounds and ear tag injuries (and horn base) by the muscid fly Hydrotea irritans causes considerable irritation that frequently results in self-trauma. Grazing patterns are disturbed and affected sheep often isolate themselves and remain in shade where available. They may stand with the head held lowered with frequent head shaking and ear movements. Alternatively, sheep adopt a submissive posture in sternal recumbency with the neck extended and the head held on the ground. Kicking at the head often greatly exacerbates damage caused by headflies to the horn base, and such action may also traumatize the skin of the neck and ears. Head rubbing also causes considerable self-trauma. Bleeding and serum exudation attract more flies and aggravate the problem. There is rapid loss of condition in severely affected sheep. Myiasis may result in some cases.		Link to Article
How can this problem be controlled?	Housing is essential for sheep with large skin lesions to allow time for complete healing. Topical emollients and antibiotic preparations are not usually necessary and skin wounds heal well provided flies are denied access to these areas. Pour-on fly control preparations, such as high cis cypermethrin or deltamethrin, must be applied before the anticipated headfly season and especially to horned sheep. Such treatments should be repeated every 3–4 weeks during the fly season or as directed by the data sheet instructions.		Link to Article