Chronic Diarrhea In Cats

Tritrichomonas foetus is a protozoan parasites of the reproductive organs of cattle that causes trichomonosis, a sexually transmitted disease. Occasionally it is iagnosed in immunocompromised humans. In cats the parasite causes chronic diarrhea (feline intestinal tritrichomoniasis). Enteral protozoa of the domestic cat are not limited to T. foetus, they include Giardia duodenalis, Cryptosporidium species. Toxoplasma gondii, Isospora species and Sarcocystis species. Co-infection of these is not unusual.

Tritrichomonas foetus is transmitted by a fecal-oral route from an infected cat to an uninfected one. The feces are yellow-green in color and foul-swelling with fresh blood, mucous, incontinence, and flatulence. The consistency of the feces is most commonly semi-formed to cow pat. Some cats have appetite loss, depression, vomiting and weight loss with occasional fever. Mortality is extremely rare and only reported in kittens. Clinical signs persist for 5 to 24 months from the time of diagnosis. Cats of one year old or younger are more susceptible to T. foetus.

Many veterinarians have observed that purebreds present more often to clinics than crossbreds due to T. foetus infections, and Abyssinians, Siamese, Bengal and Norwegian Forest in specific. Diagnosis of a trichomonad infection is made by direct fecal smear. The natural course of diarrhea in cats infected with T. foetus is waxing and waning, giving the false impression that therapy may be effective, but often relapsing after discontinuation of treatment. The most common drugs are paromomycin, fenbendazole, furazolidone, nitazoxanide, metronidazole, tinidazole and ronidazole. Ronidazole is not registered for human or veterinary use and informed consent is necessary before using it in cats and should only be prescribed in confirmed cases.

Tritrichomonas foetus


  1. Tritrichomonas foetus infection, a cause of chronic diarrhea in the domestic cat. Chaoqun Yaocorresponding and Liza S Köster

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