Cryptosporidiosis in Cats

Cats with compromised immune systems due to underlying illnesses such as feline leukemia virus infection, as well as cats that are very young or very old, are at greater risk for infection and at greater risk of more severe reactions to infection than otherwise healthy cats. This parasitic infection can even be life-threatening to a cat with other underlying health problems. Infection by this intestinal parasite is somewhat common in cats. Veterinary studies have found that around 15 percent of cats have either been infected by Cryptosporidium or are currently infected. Although this intestinal parasite is considered to be self-limiting, meaning that eventually, the infection will “run its course” even if untreated, because of the possibly serious health threat of dehydration, if your cat is experiencing severe and consistent diarrhea, it is important that your cat is seen immediately by a veterinarian.

Cryptosporidia are parasitic microscopic protozoa that infect the cells of the intestinal walls in various animal and human hosts. The Cryptosporidia are encased in protective shells called oocysts, which can be passed out of the body in the feces of the infected host. These oocysts can survive for long periods of time outside a host’s body. When the contaminated feces comes in contact with water or food sources, animals or humans that consume the contaminated food or water may then become infected with the parasite. It must be noted, however, that different Cryptosporidia are a threat to different animal species. The particular Cryptosporidia that are a threat to cats are classified as Cryptosporidium felis. When a cat ingests food or water that is contaminated with Cryptosporidium felis, the parasite infects the cells of the mucus on the walls of the small intestines, which causes the cat’s body to respond with severe diarrhea in an attempt to rid the body of the parasite. This diarrhea often results in severe dehydration. 

The symptoms experienced by a cat that has been infected with this intestinal parasite are similar to what humans often experience as the “stomach flu.” These symptoms are as follows:

• Severe diarrhea
• Stomach cramps and pain
• Nausea
• Vomiting
• Fever
• Dehydration
• Lethargy due to dehydration
• Loss of appetite
• Weight loss
• Possible rectal inflammation and bleeding due to diarrhea

The cause of intestinal parasitic infection in cats is the ingestion of food or water that is contaminated with feces that contains the oocysts of the protozoa classified as Cryptosporidium felis. When the contaminated food or water enters into the cat’s small intestines the Cryptosporidia infect the cells of the mucous lining of the small intestines. The infection worsens as the Cryptosporidia reproduce. The cat’s body reacts with diarrhea in an attempt to rid the body of the parasite.

Definitive diagnosis of cryptosporidiosis must be accomplished by a trained veterinarian. Even so, diagnosis can sometimes be difficult. Microscopic identification of Cryptosporidia requires examination by a trained and experienced veterinarian or laboratory technician. At times, although definitive diagnosis may prove to be impossible, your veterinarian may make a tentative diagnosis based on the cat’s symptoms and choose to treat the intestinal parasitic infection accordingly. The diagnostic tools available to your pet include the following:

• Listening to your observations of the cat’s symptoms
• Thorough physical exam
• Fecal smear testing (Acid-fast stains can be applied that turn the oocysts red, or Fluorescent antibody tests)

Although this infection is considered self-limiting, there are a few treatments that veterinarians can implement in an attempt to relieve the symptoms of diarrhea and dehydration while the infection runs its course. These methods of treatment are as follows:

• Increased fluid intake for rehydration, which may include feeding the cat increased amounts of moist foods during the infection
• In extreme cases, intravenous fluids may be administered
• Paromomycin, an antibiotic, may be administered but does carry the risk of renal failure in some cats
• Tylosin, an antibiotic that can be effective for treating inflammation in the intestines of small animals, may be prescribed

Even with treatment, a Cryptosporidium infection may last as many as 7-14 days. The long-term prognosis, however, for a cat that is otherwise healthy is usually very good, especially if the cat is able to receive increased fluid to address the dehydration and antibiotic treatment to combat the severity of the diarrhea. Cats that are immunocompromised, however, may have a more difficult time recovering from the infection. In severe cases of intestinal parasitic infection in cats of poor health, the prognosis may be very negative, possibly contributing to their death. All cats that are experiencing this condition need increased fluid and rest, and should be isolated from other animals, especially other cats.

It is difficult to prevent the spread of Cryptosporidium infection because this parasite cannot be killed by most disinfectants and is even able to survive chlorine treatment in water. The most effective means of prevention is keeping your cat(s) indoors where you can better control the quality of their food and water.

Cryptosporidiosis in cats can be expensive to treat. If you suspect your cat is at risk of contracting cryptosporidiosis, start searching for pet insurance today. Brought to you by Pet Insurer, Wag! Wellness lets pet parents compare insurance plans from leading companies like PetPlan and Embrace. Find the “pawfect” plan for your pet in just a few clicks!