Coccidia in Cats

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Coccidia are one-celled organisms that cause a gastrointestinal infection known as coccidiosis. The microscopic parasites, which live inside the gastrointestinal tract, can cause gastrointestinal distress, but in some cases coccidiosis can be asymptomatic.

There are numerous species of coccidia that can infect an animal; all species are host-specific. Two of the most common species in cats are Isospora felis and Isospora rivolta, which a veterinarian can identify by shape and size (although treatment is the same for both species).

Coccidia can infect any cat, although very young and very old cats, cats living in crowded conditions (such as shelters and breeding facilities), and cats that are stressed are the most susceptible to developing an infection.

Signs & Symptoms of Coccidia in Cats

Because coccidia live in an animal’s intestinal tract, and diarrhea is one of the symptoms, coccidia can be confused with intestinal worms. But they aren’t worms at all: they’re microscopic parasites that live within the cells that line the intestines.

In severe cases of coccidia, the most common clinical sign is diarrhea, which can be watery with mucus or blood. Other common signs include the following:

  • Weight loss
  • Dehydration
  • Anemia
  • Possible fever
  • In some cats, neurological problems such as depression

Not all felines infected with coccidia will develop symptoms. Asymptomatic cats are generally not in any danger unless their immune system is compromised in other ways. However, asymptomatic cats can still spread the infection to other cats.

How Did My Cat Get Coccidia?

Coccidia infections develop when a cat swallows oocysts (immature coccidia) that are found in infected feces or any environment contaminated with infected feces. Coccidia are capable of surviving long periods of time outside of the cat’s body.

The parasite can also live in the muscles of rodents such as mice; therefore, a cat that hunts and eats mice can become infected that way.

Direct contact is not required for the infection to spread. A cat can track microscopic spores out of the litter box and all through the house, which can then result in possible infection.

Kittens can catch coccidia from their mother. If the mother is shedding oocysts, the kitten can become infected through nursing or from exposure to her feces. Kittens are also more at risk in general because they have under-developed immune systems, which means they have a much harder time fighting off infection.

Diagnosing Coccidia in Cats

The most common way to diagnose coccidia is with a fecal flotation test. This test is performed to help identify internal parasites or worms. A fresh stool sample is taken from the cat and mixed with a solution made of salt or sugar, which causes the parasites and their eggs to float to the surface. Once that happens, they are examined more closely under a microscope.

If parasites are detected, the sample is deemed positive. However, if none are present, it does not automatically mean the test is negative. While it could be that there are no parasites in the intestinal tract, it could also mean that only a few coccidia, or none at all, were in that particular stool sample. This makes it impossible to determine a negative diagnosis with 100% certainty.

However, if the test is performed more than once on multiple stool samples and no parasites are found, it’s safe to say that the cat is not shedding the organisms.

Treating Your Cat for Coccidia

In most cases, coccidia is treated with an antibiotic. In severe cases, when a cat is dehydrated, supportive fluid therapy may also be administered. Not all cats will need treatment, because they usually eliminate the infection themselves.

If your cat is prescribed an antibiotic, be sure to complete the entire course of treatment as directed by your veterinarian, even if symptoms have cleared up.

Is There a Cure for Coccidia?

Yes. Coccidia may resolve even without treatment, but administering an antibiotic such as trimethoprim-sulfonamide can help resolve clinical signs faster and either limit or stop the spread of environmental contamination completely.

Is Coccidia Contagious for Humans and Other Pets?

Coccidia can infect cats, dogs, and even humans. Fortunately, host animals are usually affected by different species of coccidia, which means that spreading the infection between different species (e.g. from cat to dog) is highly unlikely.

However, keep in mind that coccidia is contagious among animals of the same species.

What is the Cost of Treating Coccidia?

The cost of treatment includes charges for the office visit, diagnostic testing, and, if needed, medication. The fecal flotation test can range from between $30 and $55, sometimes higher, depending on geographic location. (The cost of living is much higher in larger cities, and that includes the cost of health care for your pet.)

Recovery and Management of Coccidia

For cats with coccidia, the prognosis for recovery is positive; most cats are able to clear the infection. Kittens are at a higher risk for more serious complications, or even death, because their immune systems are not strong enough to fight off infections. That’s why it’s important to be aware of the possible signs and symptoms.

It’s a good idea to have another fecal test performed around the two-week mark after treatment begins, to ensure the cat has completely cleared the infection.

If antibiotics have been prescribed, be sure to complete the entire course as directed by your veterinarian, even after your cat’s symptoms start to clear up.

Preventing Coccidia

Good hygiene practices are important when it comes to preventing the spread of coccidia. Feces should be removed from litter boxes at least once daily; the quicker the disposal, the lower the risk of transmission. This is especially important in large facilities such as kennels and shelters.

Oocysts are extremely resistant to most disinfectants, so thorough cleaning (i.e. “elbow grease”) and removal of any organic debris is very important. High-heat steam is the most effective way of destroying oocysts on contaminated surfaces. Kennels, cages, beds, dishes, and even utensils must be disinfected daily. Coccidia spores can live for more than a year, which makes eliminating them extremely difficult.

Is There a Vaccine for Coccidia?

Currently, there is no vaccine to prevent coccidia.


Coccidia infections (also known as coccidiosis) can cause gastrointestinal problems, such as diarrhea. While some cats can eliminate the parasite themselves, others may need antibiotics to cure the infection, and kittens in particular are at a higher risk of complications. Staying vigilant about hygiene, by frequently removing feces and cleaning the litter box thoroughly, can help decrease the risk of infection.

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