Ameba Infection in Cats

By PetMD Editorial on Oct. 11, 2012

Feline Amebiasis

Amebiasis, a parasitic infection caused by a one celled organism known as an ameba, can affect people as well as dogs and cats. It is found most often in tropical areas and can be seen in North America.

Symptoms and Types

Entamoeba histolytica is the species of ameba which has the ability to infect cats. Infection results in colitis causing severe intractable diarrhea. Blood in stool may also be associated with amebiasis.


Entamoeba histolyticus is most often spread through the ingestion of infected human feces. Young cats and those that are immunosuppressed are the most likely to become ill.


Blood testing (complete blood cell count and blood chemistry profile) and urine testing (urinatlysis) are usually performed and are often normal although evidence of dehydration, if present, can be seen in these tests.

Other laboratory tests your veterinarian may recommend include:

  • Biopsies of the colon obtained by colonoscopy (examination of the colon with a long cylindrical scope with a light.) Biopsies may reveal damage to the intestinal lining as well as trophozoites (a stage in the life cycle of the infecting organism.)
  • Fecal examination looking for trophozoites. Trophozoites can be difficult to find in the feces. Special stains are often used to increase their visibility.


Metronidazole is used to control the symptoms of colitis and is usually successful.

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