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Dirty water is a prime coccidiosis risk factor

As spring progresses we will occasionally hear or see the complaint about suckler calves having a bloody scour, poor thrive and maybe tenesmus (forcing). One of the common causes of these clinical signs is coccidiosis caused by a protozoan parasite of the eimeria species. It is a condition that affects calves indoors but also after turnout to pasture. They ingest the oocysts in the house, but wait until they get outside before they show clinical signs. They can also ingest the oocysts outside if conditions are favourable, however the house is the main source.

Often the cause is oocysts from the environment shed by the calves' dams. As time goes on the levels of oocysts in the environment build up leading to clinical signs in the infected calves.

This is a disease that takes up to three weeks before clinical signs appear and usually affects calves between 3-12 weeks.

The oocysts, or eggs, invade the lining of lower intestine and cause damage leading to diarrhoea and poor thrive. So it is typically a disease that emerges where large numbers of calves are housed and there is a big build up of these coccidian oocysts in the environment. But it can affect animals at pasture as well and I often see creep fed calves being exposed to this disease.

The fact is that there is a risk of coccidiosis anywhere faeces builds up.

The only source of spread is ingestion of faeces containing oocysts. This is why creep feeders should be moved regularly and water sources should be free from leaks to prevent favourable conditions for the disease.

A huge contributing factor can be faeces in water drinkers. This is mainly a problem indoors but farmers should be vigilant for the clinical signs that can appear when calves are turned out.


There can be variations in the type of scour and symptoms, but it is often darker than normal, and it can have some fresh blood in it.

Sometimes I see faecal staining on rear-ends and mild scours in poorly thriving calves. In severe cases you will see animals forcing and losing weight quiet rapidly.

I usually diagnose on the basis of the clinical signs, but I also take a couple of faecal samples for the lab to rule out other issues. Once confirmed, treatment of both affected animals and the in-contacts begins.

It is important to look at husbandry and controlling the build up of oocysts in the environment once coccidiosis is diagnosed.

These oocysts can survive for up to two years so sheds need to be cleaned more regularly and avoid areas of heavy faecal build up around drinkers and feeding equipment.

Only a few disinfectants are licensed to kill oocysts in the environment so it is important to talk to your vet about these. The one I recommend to kill oocysts in the environment is Kilcox Xtra.

On the calves we often use a product containing toltrazuril such as Baycox Bovis. These calf products are prescription only medicines (POMs) so talk to your vet about which one is best for your herd.

In addition, I often recommend an oral sulpha powder, oral rehydration therapy, and pain relief since this can often be a very painful condition.

These preventative products can also be used to prevent coccidiosis before three weeks of age.

If you have a history of coccidiosis in calves I would advise talking to your vet about using these preventative medicines before problems arise.

Improving husbandry can also make huge differences to the levels of oocysts in the environment.

Indo Farming