Tritrichomonas foetus is an important and common parasitic infection of domestic cats. The parasite can cause severe inflammation of the colon and subsequent diarrhea, resulting in discomfort for the infected cat and frustration for the owner. Eradication of the infection is challenging for veterinarians and breeders alike. Different drugs have been tried for the treatment of T. foetus infection, but with limited success. The current standard of care is ronidazole, but treatment failures are common and drug resistance has been demonstrated in laboratory tests. The researchers have generated a new collection of over 1,000 promising antimicrobial drug candidates similar to ronidazole. Many of the candidates have enhanced activities against other parasites commonly treated with ronidazole and similar drugs. The objective of this proposal is to test their entire drug collection for superior activity against T. foetus and to begin assessing the best compounds for activity in a novel rodent model of intestinal T. foetus infection. Data from these screening studies will be critical for developing the best drug candidates as novel veterinary medicines for the improved treatment of drug-‐resistant feline T. foetus infection.