Coccidia in Cats

Causes, Treatment, and Prevention

Ginger cat relaxing
Mizina / Getty Images

Coccidia may not be visible to the naked eye but that doesn't mean it can't cause problems in your cat. This microscopic parasite infects the intestinal tract of cats and other species and causes coccidiosis, a condition of the intestinal mucosa. It can exist undetected in your cat so it's important to know how to see if your cat is infected and how to treat it.

What Is Coccidia?

Coccidia is a type of single-celled organism that is an intestinal parasite, but it is not a worm or an egg. There are many different species of coccidia but two species of coccidia are most common in cats: Isospora felis and Isospora rivolta. These parasites live in the cells of the intestines. It's inevitable that a cat will become infected with the Isospora felis species at least one time in its life.

Toxoplasma and Cryptosporidium are also species of coccidia but the Isospora species are the ones that are most typically referred to as coccidia. Toxoplasma and Cryptosporidium are much less common than regular Isospora coccidia in cats.

Symptoms of Coccidia in Cats

Like other intestinal parasites, coccidia commonly affects the stool of an infected cat. However, many cats that are infected with coccidia do not have diarrhea or any other clinical signs. If there are going to be signs of the illness, the symptoms will begin to show up about 13 days after the cat ingests the parasites. Call your vet if your cat is showing any of the following symptoms of coccidia:


  • Diarrhea
  • Crying when defecating
  • Sensitive when its belly is pressed
  • Dehydration with sunken eyes
  • Skin tenting
  • Vomiting
  • Loss of appetite/lethargy


Most cats that are showing symptoms of a coccidia infection will have watery diarrhea. Sometimes blood will appear in diarrhea. This is an obvious symptom but many different problems and diseases can cause abnormal stools. It may also be difficult to spot diarrhea if your cat regularly covers its stool in the litter box. Look for signs of discolored fur around your cat's back end that may harbor remnants of liquid fecal matter.

Crying When Defecating

If a coccidia infection worsens, a cat may have abdominal discomfort and cry when defecating. Persistent diarrhea may have caused inflammation in the rectal and anal areas.

Sensitive Belly

A cat with coccidia has parasites in its intestinal tract which will cause pain in the abdomen. Your cat may then become distressed when its belly is pressed.

Dehydration and Sunken Eyes

If diarrhea is left untreated, dehydration can occur resulting in sunken eyes and skin tenting.

Skin Tenting

Dehydration causes skin tenting, which is most obvious when it's observed over the shoulder blades. To tell if your cat has skin tenting, lift your cat's skin between the shoulder blades. If the skin forms a tent-like shape and stays that way for a second or more instead of immediately snapping back onto the body, the cat may be dehydrated.


With severe infections, coccidia can also cause vomiting, which can make dehydration worse.

Lethargy/Loss of Appetite

In Toxoplasma infections, cats may show a lack of appetite and become lethargic due to intestinal distress, but like cats with infections of other types of coccidia, most show no symptoms at all.

What Causes Coccidia in Cats?

For a cat to become infected with coccidia, it needs to consume the parasite. This is most commonly done when a cat ingests an infected mouse or another cat's feces. When a cat swallows the oocyst, which is the immature, infectious form of coccidia, the cat develops coccidiosis. A mother cat with coccidia can also transmit it to her kittens. A newborn kitten will begin to show symptoms when it's two weeks old.

How Do Vets Diagnose Coccidia in Cats?

If your cat is showing any signs of coccidiosis, your veterinarian will check your cat's feces under the microscope to look for coccidia oocysts (cysts containing the parasite). This parasite is very tiny compared to other intestinal parasites and can be easily missed so a very thorough fecal analysis, or multiple fecal analyses, must be performed to find it.

If your veterinarian is concerned that your cat may have one of the less common types of coccidia such as Toxoplasma or Cryptosporidium, they may need to run additional specific tests. A series of blood or fecal samples are often taken in those cases.

How to Treat Coccidia

To treat coccidiosis in a cat showing symptoms, your cat will need a specific type of anti-parasitic medication to kill the parasite. Usually, a drug called trimethoprim-sulfonamide is prescribed and given orally to your cat for about a week or up to 20 days to treat the infection. Even with treatment with certain medicines, there is the potential for persistent low-level traces of the infection until it is completely eradicated. Probiotics, prebiotics, and special diets may also be needed.

Prognosis for Cats with Coccidia

The outcome is good for cats appropriately treated with coccidia. Most cats with strong immune systems seem to spontaneously get rid of the parasite on their own by shedding it in their stool. While coccidia is a very common parasite in cats, many do not require treatment if they aren't showing symptoms. On the other side of the spectrum, a severe coccidia infection may be fatal to kittens and adult cats with other health issues.

How to Prevent Coccidia

You can prevent your cat from contracting coccidia by taking preventative measures. Though you can't guarantee that your cat will never get the parasite, you can take the following steps to minimize the risk:

  • Keep your cat indoors—it is the best way to prevent your cat from getting coccidia.
  • Stop your cat whenever you see it hunting or playing with a mouse it has caught indoors or outdoors.
  • Quarantine a cat showing symptoms and keep it away from the litter box, food, and water dishes that the other cats in your household use. Unfortunately, the oocysts may not always respond to cleaning disinfectants.
  • Avoid feeding your cat uncooked meat which can also decrease the likelihood that it will ingest coccidia oocysts (cooking meat to its appropriate temperature can kill oocysts). If you are feeding your cat a raw diet, understand that it comes with risks, such as coccidia.
  • Bring any new kitten you have adopted to the vet right away to check for any symptoms of the illness.

Is Coccidia Contagious to Humans?

The common Isospora types of coccidia are not a concern for humans but if your cat is diagnosed with Toxoplasma or Cryptosporidium you can potentially become infected. Immune compromised individuals have the highest risk of infection but by practicing good hygiene techniques and properly disposing of cat feces you can minimize the risk of contracting these zoonotic diseases.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.
Article Sources
The Spruce Pets uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Toxoplasmosis in Cats. Cornell University College of Veterinary Medicine.

  2. Coccidiosis in Cats. VCA Animal Hospitals.

  3. Coccidiosis in Cats. VCA Animal Hospitals.

  4. Coccidiosis in Cats. VCA Animal Hospitals.

  5. Zoonotic Disease: What Can I Catch From my Cat? Cornell University College of Veterinary Medicine.