August 2023

Coccidia is a single celled gut parasite which usually affects calves between 3-8 months of age. While it usually occurs in older animals, it can affect those as young as 4 weeks. The effect of this parasite on stock can vary. It can be subclinical, in that a given animal can be infected but not show any outward signs of ill health. On the other end of the spectrum, coccidia can lead to significant gut upset, growth checks, and even the death of those affected. The severity of symptoms seen depends on the animal’s immune system and how heavy the coccidia burden is. Coccidia has a more detrimental effect on health when it is seen alongside the following conditions: increased stress, poor nutrition, and diseases (such as BVD). Symptoms are usually seen ~2 weeks after exposure.

Symptoms commonly seen:

  • Faecal staining around the tail and on the backs of the legs
  • Faeces that contain mucous and blood
  • An animal that is repeatedly straining to defecate
  • Elevated temperature (39.0-39.5 ⁰C)
  • Animals appear uncomfortable/listless
  • Rapid weight loss
  • Decreased appetite

Coccidia uses the cells in the intestines to reproduce, destroying them as they emerge. This effectively damages the intestinal lining, decreasing the ability of the animal to absorb nutrients and retain water. Hence the weight loss and dehydration, despite good feed availability. These signs can continue for typically 7-10 days, after which, in the absence of reinfection, the calf will often begin to recover. However, depending on the degree of damage, it can take weeks for the gut to recover and until it does, feed intake and weight gains will be reduced.

Like a lot of the parasites we deal with, coccidia is shed in the faeces and infection occurs via ingestion of contaminated pasture, feed and water. Infection can also occur through grooming, again via inadvertent ingestion of contaminated faeces that are on the animal’s coat.

Coccidia is a hardy organism, being able to survive in pasture for up to 2 years when the conditions are not too dry or hot. If the same paddocks are used for calves from year to year and the weather conditions mild, coccidia outbreaks can be seen. Outbreaks can also occur when the feeding of coccidiostat containing feed stops as it takes time for calves to build an immunity to coccidia.

If you suspect stock may have coccidia, you can bring in a fresh faecal sample to check for coccidia.

As coccidia can infect a significant proportion of animals in a mob without all of them showing signs of obvious sickness, a big part of management is prevention. This involves feeding milk and meal with coccidiostats in them and using drenches that are also effective against coccidia. Preventative management practices revolve around rotational grazing if applicable and ensuring an appropriate stocking density. Where animals are ill, treatment involves separating them from the rest of the mob and oral dosing them with toltrazuril (BaycoxC) which is usually given as a one-off treatment. Most animals should recover if caught and treated early.