Efficacy of a 3C-like protease inhibitor in treating various forms of acquired feline infectious peritonitis

Pedersen, Niels C; Kim, Yunjeong; Liu, Hongwei; Galasiti Kankanamalage, Anushka C; Eckstrand, Chrissy; Groutas, William C; Bannasch, Michael; Meadows, Juliana M; Chang, Kyeong-Ok

Cat CT12 responded well to treatment at a dosage of 15 mg/kg q12h SC; the rectal temperature returned to normal within 48 h and the abdominal effusion disappeared within 2 weeks. The cat appeared normal after the second week of treatment but then developed a persistent fever of 102.5-104°F. The owners felt that the cat was otherwise normal in activity and appetite so the treatment was continued at the same dosage. However, the fever persisted, subtle behavior signs were noted and the cat failed to grow as expected. The cat continued treatment for 15 more weeks during which time the drug dosage was transiently decreased twice (ie, to 10 mg/kg q12h and 15 mg/kg q24h) for several days, but the fever increased and activity decreased each time and the 15 mg/kg q12h dosage was reinstituted. The cat continued to show signs of variable fever and vague behavioral signs, but the owners were optimistic about the cat's appetite and level of activity. The cat's treatment was then stopped as further use of the drug for this purpose could not be justified. The cat's condition remained unchanged with persistent fever, reclusive behavior and failure to grow for another 5 weeks. Severe neurologic signs consisting of incoordination, dementia and seizures appeared at week 22 and the cat was euthanized. Gross and microscopic lesions were limited to the brain.