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

The present study was limited to 20 cats with FIP, representing a spectrum of ages and disease forms. Although the number of treated cats was small, a surprising amount of information was gleaned, such as how long to treat, potential side effects, how to identify the clinical form of FIP most likely to respond to the therapy, and potential indicators for treatment failures and successes. The field study was based on the experiences gained from pharmacokinetic and efficacy studies undertaken in laboratory cats. The initial treatment period was set to be 2 weeks based on experimental studies, but it was ultimately extended to 12 weeks and longer based on experiences obtained as the trial progressed. This final treatment period was closer to the 3-6 months used to treat HCV infection in people with direct-acting antiviral drugs. 2 Difficulties in treating neurologic disease was also anticipated from experimental studies. Side effects were acceptable and included stinging upon injection and dermal and subcutaneous inflammation when too much drug was given in the same spots. This was also seen first in laboratory cats. A more serious side effect, which was not seen beforehand in laboratory cats, was limited to kittens and involved retarded development of adult teeth and retention or delayed loss of deciduous teeth.