Intestinal Virus Due to Bacterial Overgrowth (Astrovirus) in Cats


PetMD Editorial

Updated Aug. 24, 2022

Astrovirus Infection in Cats


Astrovirus infection is a genus of small, non-enveloped RNA virus that causes intestinal disease symptoms in affected animals. Characteristic symptoms include diarrhea and abdominal pain with watery, green diarrhea. If the diarrhea lasts longer than a week, then it is probably not caused by astrovirus, as the astrovirus generally passes in less than a week.


While the astrovirus by itself is not dangerous, dehydration due to lack of fluids and diarrhea can quickly become a dangerous condition. However, fluids can be given on a temporary inpatient basis to help the cat recover.


This virus is relatively rare in cats, and shows no tendency for infecting a particular breed, gender, or age. And although the astrovirus infection is communicable amongst cats, it is not communicable between cats and humans.


Symptoms and Types


  • Green, watery diarrhea
  • Dehydration (check for sunken eyes)
  • Anorexia (no appetite)
  • Fever
  • Abdominal pain
  • Often more severe in kittens




What causes a cat to become infected with the astrovirus is unknown, but it is an infectious virus that is acquired from another cat.




You will need to provide a thorough history of your cat's health leading up to the onset of symptoms. Your veterinarian will then perform a thorough physical exam, a blood profile, and a complete blood count. 


With gastrointestinal diseases, a swab of feces needs to be taken for laboratory analysis. A differential diagnosis, which is guided by deeper inspection of the apparent outward symptoms, ruling out each of the more common causes until the correct disorder is settled upon and can be treated appropriately, will include tests for the presence of parasites (e.g., intestinal worms), toxic ingestion, food allergy, and other viral infections that could be responsible for the symptoms. These include rotavirus, panleukopenia, or enteric coronavirus, all of which can cause the same types of symptoms.


The physical exam and complete blood count will indicate to your veterinarian if and to what degree your cat is dehydrated, and how severe the infection is based on how high the white blood cell count is. The blood profile will let your veterinarian know if the diarrhea is caused by a bacteria or a virus.




Treatment will depend on the final diagnosis. If your cat is dehydrated due to the diarrhea and lack of fluids, it will receive fluids to rehydrate it immediately. Medication can also be given to control the diarrhea. Your veterinarian may also prescribe a special, bland, easily digestible, high protein veterinary diet tailored for cats with intestinal upset.  


Living and Management


If astroviral infection is suspected in your cat, then you will need to keep your cat away from all other cats until the infected cat no longer has diarrhea or is displaying any other symptoms. 

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