Tritrichomonas foetus: a new agent of feline diarrhea.

Tritrichomonas foetus is a single-celled, flagellated protozoal parasite that colonizes the feline colon and distal ileum. Infected cats may be asymptomatic or may have clinical signs that include malodorous large bowel diarrhea. T. foetus infection is common in, but not limited to, high-density populations of young, purebred cats. Testing for this parasite is still not routine at most veterinary clinics, and T. foetus is often misdiagnosed as Giardia spp. T. foetus-specific tests (fecal culture and polymerase chain reaction) should be considered in cats with large bowel diarrhea, especially those in which traditional diagnostics and treatments for other causes of feline large bowel diarrhea have failed to reach a clinical resolution. Recognition of this newly emerging disease and appropriate sample handling are critical for the detection and treatment of feline trichomoniasis.