Ronidazole is a nitroimidazole antibiotic/antiparasitic drug thatappears to be useful in treating ritrichomonas foetus infections incats. The drug is also used for treating Trichomonas infections in nonfood animal birds. Ronidazole, like other 5-nitroimidazoles such as metronidazole is converted by hydrogenosomes (an organelle found in trichomonads) into polar autotoxic anion radicals. T. foetus infections in cats have been resistant to treatment by metronidazole, but ronidazole appears to have greater activity against the organism.