Coccidia in Cats

What Is Coccidia in Cats?

Coccidia are single-celled (protozoan) parasites that nearly all cats are exposed to in their lifetime. The parasite travels into the intestinal lining cells of the cat, where it matures over about two weeks into oocysts, rupturing the cells and causing intestinal damage. These oocysts then pass through the intestines into the stool to finish their life cycle, become infective (sporulate), and spread into the environment. It takes no more than 16 hours for a passed oocyst to sporulate into an infective state. Once in that state, they can survive for up to year in temperate environments.  

There are many species of coccidia that infect many different animals, but almost all these parasites are host-specific, meaning a cat cannot transmit an infection to a dog or human, they can only transmit it to other cats.

Symptoms of Coccidia in Cats

An infection with coccidia does not always mean an illness is present. Many cats will eliminate the parasite on their own while others may shed oocysts in their stool without ever showing symptoms (asymptomatic). When illness (coccidiosis) does occur, it is often in young kittens or older cats with poor immune systems. 

As the life cycle of these parasites occurs in the intestines, signs of illness are related to the digestive system. Diarrhea is most common and may be associated with weight loss. Cats can become dehydrated (especially young kittens), and reluctant to engage in normal, playful behaviors. Only in rare cases will there be vomiting and loss of appetite. These symptoms may be aggravated by stressful environmental changes like adoption, weaning, or living in an animal shelter.

Causes of Coccidia in Cats

Most cats, particularly those who spend time outdoors, pick up this parasite from their environment, grooming it off their fur and feet.

Mice, rats, and other common prey species are known as transport hosts because they can carry certain life stages of coccidia, which then infect the cats who hunt them. Cats who share a litterbox with an infected cat risk picking up the parasite themselves, even if they do not hunt or go outside.

How Veterinarians Diagnose Coccidia in Cats

A veterinarian will take into consideration the cat’s history, symptoms, and use a microscope to determine if oocysts are present.  

Coccidia is diagnosed through a stool sample. In this testing, fecal matter is mixed with a special solution that allows the oocysts to float to the surface, where they can be collected on a slide and examined under a microscope. Each species of coccidia has a unique oocyst appearance that can be identified.  

Treatment of Coccidia in Cats

Coccidia is usually eliminated in cats with an oral antimicrobial medication. Sulfadimethoxine (Albon®) is the most commonly used product, though there are other medications that may be recommended. 

Depending on the severity of the cat’s illness, antimicrobial treatment is often combined with medications to help alleviate symptoms, such as probiotics, low residue diets, anti-nausea medications, and fluid therapy.  

Recovery and Prevention of Coccidia in Cats

Cats that are properly treated and supported typically make a full recovery from coccidiosis.  

Daily removal of feces from the litterbox, routine cleaning of the environment, and treating all cats in contact with the infected cat are recommended to prevent the spread of disease.

Cats with outdoor access and cats who like to hunt should have fecal flotation tests completed annually to look for asymptomatic infections.