Cryptosporidium in Cats: Prevention and Common Symptoms

If your cat has diarrhea, a common intestinal parasite called cryptosporidium may be the cause.  

Cryptosporidium in cats is a contagious protozoal infection that often causes mild diarrhea, though some cats—especially kittens, stressed cats, and those with weakened immune systems—can develop more serious symptoms. 

Many infected cats never show signs of illness and may clear the parasite on their own. However, persistent diarrhea, vomiting, lethargy, or signs of dehydration should prompt a veterinary visit. Understanding the symptoms, causes, treatment options, and prevention strategies can help protect your cat and support a faster recovery. 

What Is Cryptosporidium in Cats?

Cryptosporidium is a protozoan parasite. Protozoa are single-celled organisms, and there are many different species. The type that most commonly affects cats is called Cryptosporidium felis. While C. felis prefers cats, humans can occasionally become infected with this parasite. 

Cats infected with cryptosporidium often show no symptoms at all. 

When symptoms of cryptosporidium in cats do occur, diarrhea is the most common sign. 

The parasite releases small cells called sporozoites in the intestines, which irritate the intestinal lining and interfere with the absorption of nutrients. 

In many cases, the diarrhea will resolve on its own as the cat’s immune system fights off the parasite. In other cases, affected cats may require treatment. 

Cryptosporidium usually causes mild diarrhea and is not typically considered an emergency. However, severe diarrhea accompanied by vomiting, lethargy, or loss of appetite can quickly lead to dehydration and should be treated as an emergency. 

Symptoms of Cryptosporidium in Cats

While some pets may show no symptoms, common signs of cryptosporidium in cats include: 

• Diarrhea 

• Weight loss 

• Decreased appetite 

• Lethargy 

• Vomiting 

• Elevated third eyelids 

• Dry, tacky gums 

Causes of Cryptosporidium in Cats

Cryptosporidium in cats spreads when cats ingest infected fecal particles.

This most commonly occurs when cats share litter boxes and then groom themselves afterward. 

Sharing food or water bowls and mutual grooming with an infected cat can also spread the parasite.

Rarely, cats can contract cryptosporidium by hunting and eating infected prey, such as birds or rodents.

Young and stressed cats are more likely to develop cryptosporidium infections because their immune system is either immature or weakened. Cats with underlying illnesses are also at increased risk because their immune system is already working to fight other conditions.

Shelters, rescues, and other environments housing many cats are more likely to experience cryptosporidium outbreaks due to the close contact between animals. 

How Veterinarians Diagnose Cryptosporidium in Cats

To diagnose cryptosporidium in cats, your veterinarian will begin with a physical exam. If intestinal parasites are suspected, fecal testing is typically recommended. 

Before your veterinary visit, try to obtain a fresh stool sample and bring it with you. If your cat uses the litter box the morning of or the night before the appointment, collect the stool in a sealed bag. Double-bagging and refrigerating the sample until the appointment is recommended. 

Do not freeze the sample, as freezing may damage parasite eggs and interfere with testing. 

Treatment of Cryptosporidium in Cats

Treatment of cryptosporidium in cats depends on whether your cat is showing symptoms. 

If cryptosporidium is found during routine fecal testing in a cat without symptoms, treatment may not be necessary. Many healthy cats clear the parasite on their own without medication. 

If your cat has diarrhea or other signs of illness, treatment is usually recommended. 

Cryptosporidium infections are commonly treated with medications such as tylosin or azithromycin. 

Some cats with cryptosporidium also have co-infections with other parasites, such as giardia or Tritrichomonas foetus. These cats may require additional medications, including metronidazole or ronidazole. 

Most cats recover fully. If treatment is unsuccessful, your veterinarian may recommend further testing to look for underlying diseases, such as inflammatory bowel disease (IBD). 

Recovery and Management of Cryptosporidium in Cats

Recovery from cryptosporidium in cats lasts a few days to a week, though some cases take longer. Cats with concurrent infections, such as giardia, may require several weeks for full recovery. 

Probiotics may help restore healthy gut bacteria during recovery. 

Purina FortiFlora and Nutramax Proviable are commonly recommended options. 

Fiber may also help normalize stool quality in some cats. Fiber can be added through pumpkin toppers or psyllium supplements. 

Some cats also benefit from high-fiber veterinary diets, such as Hill’s Gastrointestinal Biome or Royal Canin Fiber Response. 

Prevention of Cryptosporidium in Cats

Because cryptosporidium in cats spreads primarily from pet to pet, prevention focuses on minimizing exposure to infected animals. 

Preventing hunting behavior and limiting exposure to wildlife can also help reduce the risk of contracting cryptosporidium from birds or rodents carrying the parasite. The easiest way to accomplish this is to keep your cat indoors. 

If you visit cat cafés, shelters, or other environments with many cats, wash your hands thoroughly and change clothes and shoes before returning home to help protect your cat from disease exposure.