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Could Coccidiosis be holding back your Calves?

Could Coccidiosis be holding back your Calves?

Like cryptosporidia, coccidiosis is caused by protozoa but rather than present as a problem in calves shortly after birth, coccidiosis will tend to show in calves that are slightly older. Aidan Murray, Teagasc Beef Specialist has more information on the signs, treatment and prevention of coccidiosis

Cattle will develop an immunity to the condition over time but young calves with an underdeveloped immune system placed in a dirty environment can succumb to the disease. A dirty environment leaves calves more likely to ingest high numbers of the immature protozoa and as calves get older they will have less passive immunity from the cows colostrum.

Coccidiosis tends to be seen in calves from about 3 weeks old up to about 6 months

Infected calves pass out large numbers of oocytes which can contaminate the environment for other calves. The oocytes are resistant can survive for long periods in the environment (sheds etc)

Clinical Signs

Coccidia can cause a watery scour as they damage the mucosa of the intestine. Damage to the intestine reduces the calves ability to absorb fluids and nutrients and so calves that are infected can become dehydrated, may start to pass blood, shed part of the intestine lining and can become weak and uncoordinated.

Calves that have the condition can often be seen straining. Probably the biggest economic loss is poor thrive in animals that are affected. So if you see scouring in older spring born calves at this time of year coccidiosis could be a likely cause.

In many herds there may be sub clinical infection where animals show very little symptoms and will recover with time but thrive will be affected and I have come across a number of cases where farmers have complained that ‘calves are not doing’.


If a herd has had trouble with coccidia in the past then they need to be vigilant because it can easily re-occur particularly where hygiene is poor. Good records are important.

Good management of coccidia involves allowing the calves to be exposed to the parasite to develop immunity but at the same time avoiding disease and poor performance.

Herds that have an ongoing problem with coccidiosis will often dose calves with anticoccidial products (diclurazil/toltrazuril) as a prophylactic. Typically calves will be given an oral dose of between 20-30ml depending on the weight of the calf. One dose is usually sufficient if timed correctly. Calves that are scouring become dehydrated should receive normal electrolyte therapy and be removed from the group. 

Choosing a disinfectant that is affective against oocytes is critical

Faecal samples sent to the lab from calves could quickly rule in or out if you have a coccidia problem.


  • Increase the amount of bedding used in the calf areas
  • Try and prevent the build up of faecal contamination in and around feed and water troughs
  • Avoid mixing of different ages of calves as younger calves will be more susceptible.
  • If you have had a problem make sure sheds are cleaned and disinfected between batches of calves. Choosing a disinfectant that is affective against oocytes is critical
  • Avoid overstocking of sheds.
  • Keep a record of any coccidiosis on the farm and use this information to target treatment year on year.
  • Animals can be given licenced medication as already mentioned to prevent the disease.
  • Please note that there is no vaccine available against coccidia.
  • If you think coccidiosis is an issue on your farm get your vet to investigate and they can develop a health protocol to control the problem.

Further information is available at Animal health Ireland who have published very good guidelines on the management of coccidiosis in calves.

Also check out the Teagasc Beef Manual Section Diseases of young calves for more on Clostridia and other Calf related diseases