Parasite of the month: Coccidiosis

Farm vet Bobbie Plant explains what the parasite is and how it affects sheep and cattle.

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What is it and who does it affect?

Coccidiosis is caused by infection with pathogenic species of Eimeria, a single-celled parasite. Clinical signs of disease typically include scour +/ – blood, dehydration, rapid weight loss, straining to defecate (sometimes with rectal prolapse as a result) and occasionally death. Older lambs/ calves may present with reduced daily live weight gain.

In cattle: Calves from 1 to 12 months, at any time of the year.

In sheep: Typically affects lambs between 4 and 8 weeks of age (ranging from 3 weeks to 3 months) from January to May. Disease is more common in lambs born in the second half of the lambing season.

What are the risk factors?

Risk factors fit into 2 main categories:
• Contamination – of housing, around feed areas, water troughs/watercourses.
• ‘Stressors’ – weaning, mixing groups, poor hygiene, high stocking densities, inadequate nutrition, adverse weather, castration, concurrent disease (especially Nematodirus in lambs) etc.

How do we diagnose and treat it?

We would send faecal samples to a lab for a count (number of oocytes per gram) and speciation (since not all species of coccidia are athogenic).

Where speciation indicates a non-pathogenic species, the cause of scour is not coccidiosis and so will not respond to treatment with a coccidiostat. Clinical signs of Nematodirus in lambs and Salmonella in calves are very similar to coccidiosis.

Successful treatment of disease relies upon it being early. Unfortunately, this often means initiating treatment before receiving a confirmatory diagnosis from the lab. Treatment of coccidiosis should consist of a coccidiocide (ask your vet for the most suitable option), oral rehydration and a non-steroidal anti-inflammatory drug (NSAID).

How can we prevent it?

Consider risk factors (see above). One of the most effective strategies to prevent coccidiosis is to routinely muck-out and disinfect housing between batches and keep bedding as clean and dry as possible. Where there is a known history of coccidiosis, or a group of animals is considered at significant risk of infection, the use of a coccidiostat preventatively can be justified.

IF you have any concerns or would like to know more, please contact us!

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