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

Five cats (CT03, CT07, CT10, CT14 and CT16) had recurrence of typical intra-abdominal lesions in the absence of neurologic signs during or after treatment ( Table 1) . Four of them presented with ileocecal masses (CT03, CT07 and CT14) or an enlarged colonic lymph node (CT10) that decreased in size (CT03, CT10 and CT14) or became no longer palpable (CT07) following primary treatment. However, CT03 continued to suffer from severe constipation, straining and toothpaste-like stool. The severity of the colonic obstruction necessitated a colon resection, which relieved the clinical signs but did not prevent eventual recurrence of abdominal disease. All three cats that presented with severe ileo-cecal-colic Attempts to treat neurologic disease by increasing drug dose and treatment duration An attempt was made to alleviate neurologic signs by increasing the dose of GC376, thus increasing blood levels and the amount of drug that passed across the blood-brain barrier. Cat CT01 presented with effusive FIP and was initially treated with GC376 (10 mg/kg q12h SC for 9 days). The cat responded well, but fever returned on day 9 and the dosage was increased to 15 mg/kg q12h for 5 days. The fever disappeared and treatment was stopped at day 14. Fever returned 3 days later along with vague neurologic signs consisting of muscle twitching, abnormal limb stretching and abnormal Each point indicates the fold reduction of viral RNA level over that measured prior to treatment (day 0). Virus RNA levels were determined using quantitative real-time PCR by the ∆Ct method and a beta-actin reference gene swallowing motions. The cat was immediately put back on treatment at a dosage of 15 mg/kg q12h SC and its condition improved but shortly worsened with return of fever and the same vague neurologic signs with mild incoordination. The dosage was then increased to 50 mg/kg q12h SC for 14 days and its condition improved to near normal. Treatment was stopped but neurologic signs immediately returned. The cat was then treated for four additional days at 50 mg/kg q12h SC, during which time the neurologic signs once again improved. However, a decision was made to stop all treatment after that time. The cat's condition remained stable for 1 week and then the cat developed extreme incoordination, dementia and tonic/clonic seizures. Euthanasia was performed and a necropsy demonstrated lesions only in the brain.