All About Coccidiosis

What is coccidiosis?

Coccidiosis is one of the most common livestock diseases. It can cause gut damage, stunted growth and can damage production profits in lambs and calves. Although it is extremely rare that coccidiosis results in death, it does reduce growth and weight gain in the animals.

There are over twenty species of coccidia that can affect livestock, only three of which are pathogenic (will cause disease). We primarily see coccidiosis in young animals who have little to no immunity. Animals develop immunity to coccidiosis over time. Many adult animals would have some coccidia in their system and they will not have any damaging effects. done.

Young animals, however, will have developed an initial small degree of immunity from antibodies they have absorbed from their mothers, but this initial protection wanes quickly. This leaves calves and lambs susceptible to coccidia infections before having a chance to build their own immunity. Typically, we see this in lambs at about four to six weeks, while in calves it is most commonly diagnosed, at three to twelve weeks. Coccidiosis is often seen within a couple of weeks of mixing groups of animals together.

The timing of a coccidiosis infection in a group of livestock is completely dependent on a number of different factors and will be different from farm to farm. However, it is important to note that coccidia causing oocysts “can build up during a housed period, increasing the risk of disease, especially as spring turnout nears” Rhian Price, Farmers weekly 12 Apr 20. Dr. Tim Potter, from Westpoint Farm Vets, part of the VetPartners group, says: “As stocking densities increase pre-turnout, it’s harder to keep sheds clean and dry, so you generally see a spike in oocyst numbers in the environment and therefore a heightened risk of ingestion by calves.”

What are the clinical signs?

There are multiple symptoms of coccidiosis. These symptoms, however, are not always specific to coccidiosis, meaning faecal samples will need to be tested. Farmers need to be aware of these symptoms and should consult with a vet if you suspect a coccidia infection in the herd or flock. However, 95% of cases are sub-clinical, emphasising the need of regular feacal testing that needs to be:

  • Dehydration
  • Diarrhoea (often very watery, +/- blood)
  • Weakness
  • Loss of appetite
  • Weight loss
  • General poor condition
  • Straining (calves with their tails up demonstrating unproductive straining)

It is important to also note, that infections that fail to produce diarrhoea can still result in a reduction of growth and weight loss. This ‘Sub-clinical’ infection is very common. Calves will not have immunity against new species.

Once clinical signs are visible, the intestinal lining will already have some damage. Therefore, identifying when the infection is occurring to enable preventative treatment during the pre-patent period (before clinical signs are apparent) can limit damage to the gut and losses. Meaning, regular testing of a group is important. 

How does infection occur?

Coccidiosis is spread through oral transmission. Most commonly it is spread by faeces. Areas that animals ingest infection form include:

  • Contaminated water troughs
  • Dirty udders
  • Sucking on dirty fences

The coccidia eggs can survive, over a year, and they can also withstand freezing temperatures. For this reason, it is important to thoroughly disinfect and clean housing between batches. If a field was contaminated the previous, year, it is very likely to turn up the following year with animal infections when they are turned out.


In the long run, if you have a lot of trouble with Coccidiosis, you will also need to look at your hygiene and management practices, in addition to choosing a suitable drench for your animals. Regular gut worm testing should also be carried out so that you can be advised by your practicing vet.

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