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Investigation of causes of "low worm egg count diarrhoea" in sheep in Western Australia

Jacobson, C.ORCID: 0000-0001-9427-1941, Bell, K., Forshaw, D. and Besier, R.B. (2006) Investigation of causes of "low worm egg count diarrhoea" in sheep in Western Australia. In: Australian Sheep Veterinarians Conference, 9 - 11 September, Wagga Wagga, Australia

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Nine flocks of sheep with "low worm egg count scouring" in the south west of Western Australia were investigated over a three-year period. There was no significant difference in the faecal worm egg counts of "scouring sheep" (diarrhoea and severe dag) compared to "normal sheep" (pelleted faeces and mild or no dag). Teladorsagia (Ostertagia) circumcincta and Trichostrongylus spp were the strongyles most commonly identified on total worm counts and differentiation of larvae recovered from faeces and pasture. Immature strongyle worms accounted for the largest proportion of total worm counts. Adult worm burdens were small in most sheep. Scouring sheep had significantly higher numbers of early fourth stage larvae. There was no histopathological evidence of bacterial or viral causes of scouring in any of the flocks that could be supported with bacteriology. Two flocks had marginal selenium status. One flock was diagnosed with helminthosis based on increased worm egg counts and high total worm counts. Larval hypersensitivity scouring, nutrition or a combination of these two factors were the most likely causes of scouring in the other eight mobs based on exclusion of other known causes of scouring. Treatment with moxidectin drench and an ivermectin controlled-release capsule did not change faecal moisture of treated sheep compared to untreated sheep three to five weeks after treatment.

Item Type: Conference Paper
Murdoch Affiliation(s): School of Veterinary and Biomedical Sciences
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