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Tritrichomonas foetus Infection in Cats

Gookin JL, Stauffer SH, Dybas D et al: Documentation of In Vivo and In Vitro Aerobic Resistance of Feline Tritrichomonas foetus Isolates to Ronidazole, J Vet Intern Med 24:1003, 2010.

One cause of chronic large bowel diarrhea in cats is a protozoal pathogen called Tritrichomonas foetus. Estimates indicate that up to 30% of purebred show cats and 29% of cats with clinical signs of infection are infected with this organism in the United States. Trichomonads like T. foetus are susceptible to the effects of 5-nitroimidazole drugs because they utilize reductive metabolic pathways. Ronidazole is the only drug demonstrated as effective for treatment of cats infected with T. foetus and resistance to ronidazole has not been reported previously. In this study, two intact male Abyssinian cats with T. foetus were found to have resistance to increasing dosages of ronidazole. Treatment with multiple courses of metronidazole and tinidazole also did not eradicate the infection. The true prevalence of treatment resistance in the infected cat population is not known. A persistent infection in treated cats should be confirmed by the results of follow-up testing rather than assumed on the basis of clinical signs. Cats should be isolated from sources of re-infection. Cross-resistance among 5-nitroimidazole drugs has been described and the current lack of alternative drugs that have clinical efficacy against feline T. foetus suggests the need for an active investigation of other treatment approaches. [VT]

Related articles:
Payne PA, Artzer M: The biology and control of Giardia spp and Tritrichomonas foetus, Vet Clin North Am Small Anim Pract 39:993, 2009.