Some aspects of coccidiosis in sheep and goats

This paper provides a brief review of the widespread and economically important disease of coccidiosis. At one time, coccidia were considered to be virtually non pathogenic, but by the 1960s they were recognised to cause disease. Almost all young lambs and kids will be exposed and become infested during their early life and there are similarities and differences between the two host species. Coccidian species are mainly identified by their morphology and the predilection site within the host's alimentary tract. At one time, it was thought the species in goats and sheep were the same, but cross transmission studies have shown that the coccidia are host-specific. Currently, 11 coccidian species are recognised in sheep and nine in goats. Two sheep species are known to be highly pathogenic and these two parasites inhabit both the small and large intestine. Much less work has been undertaken on goat coccidia, although it is considered that several Eimeria species might be pathogenic. Often, clinical signs in sheep and goats are limited and mild, but it is common for animals to decrease their weight gain or even lose weight. The faeces may alter and there may be diarrhoea. Whilst there are production losses, there has been little quantification in sheep or goats. Moreover, infested animals appear more susceptible to other infections. Diagnosis is often more difficult than it seems. Because of problems, this has resulted in suggestions that the diagnosis of coccidiosis should be based on a number of parameters: epidemiology, clinical signs, oocyst counts in faecal samples, pathological findings and, finally, clinical response to treatment. There are several preparations licensed in the United Kingdom for sheep, but none for goats. There are also several management factors which can assist in control of the disease, but often medication has to be used to prevent the disease.