Coccidiosis is a protozoal parasite that invades the lining of the guts in many species after they ingest infective oocysts (eggs) and is of particular economic importance in cattle and sheep. It causes clinical signs such as passing blood, diarrhoea, fever, inappetence, weight loss/poor growth and in extreme cases, death. However many cases are subclinical and show as poor growth rates.

It is most common in young animals that are housed or confined in small areas that are contaminated. Older animals are a source of infection and oocysts can survive well in the environment, so a burden can easily build up. Coccidia are opportunistic pathogens which are most likely to cause clinical signs when an animal has a comprised immune system. This can be related to poor nutrition, hygiene, overcrowding, stress of weaning, movement, and sudden changes in feed or severe weather.

Coccidia are host-specific with certain types causing disease in each species, three out of 12 types generally cause disease in cattle and two out of 15 tend to cause disease in sheep in the UK (http://www.nadis.org.uk/bulletins/coccidosis-in-lambs.aspx). There is no cross immunity between types of coccidia, but cattle and sheep do tend to develop immunity to the specific types if they are exposed to low levels.

Many calves and lambs will acquire infections of varying severity between the age of one month and one year. In lambs it is not common after three months of age to have obvious clinical signs, but poor growth rates associated with subclinical infection can occur. The infection rate for coccidiosis is high with commonly minimal clinical signs seen but in a group that are under stress and exposed to large amounts of coccidia up to 80 per cent of animals may show obvious signs (http://www.merckvetmanual.com/mvm/digestive_system/coccidiosis/overview_of_coccidiosis.html).

Clinical signs of straining with the passing of blood or tissue and dehydration are due to the invasion and destruction of the lining of the intestine. Oocysts are shed in the faeces so can be identified in samples, high numbers are usually indicative of disease. However there can be a delay between diarrhoea and output of oocysts, so sometimes multiple samples need to be taken from a group to confirm a diagnosis. These samples can be analysed by the Biobest lab team. The type of coccidia should be identified as pathogenic, however careful interpretation of farm history, clinical signs and faecal analysis, along with if any post mortems are performed can lead to a diagnosis.

Coccidiostats such as diclazuril or toltrazuril can be used for treatment of individuals showing clinical signs, along with supportive fluid therapy. It is also sensible to isolate affected animals, if possible to reduce exposure to others. Treatment is most effective when given soon after infection, hence it is important to consider treating at risk animals to reduce effects and to limit further shedding in to the environment. This can be discussed with your vet to decide when it is most suitable as there are in feed products available for use on larger scales (decoquinate), as well as oral products that are generally more suitable in the face of an outbreak and in animals that are too young to be eating solid food.

Prevention is based on good management of young animals and their environment, to minimise exposure to coccidia so that immunity can build up but not cause problems. Ensuring young animals are well nourished and in clean and dry environments will make them less likely to succumb to coccidiosis or in fact many other infections. Weight loss and a long recovery process may lead to lower weaning weights of calves and lambs, reducing profits along with higher costs associated with treating groups of animals. Therefore it is important to be in control of coccidiosis from a welfare and economic perspective.

For further information on Westpoint, please contact our Launceston practice on 01566 86985, or visit www.westpointfarmvets.co.uk.

For further information on Biobest and the tests available, please visit www.biobest.co.uk.