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 bodies of 12/13 cats that ultimately failed treatment were submitted for necropsy including gross and histologic examination and immunohistochemistry on diseased tissues for FIPV antigen. Tissues collected and examined included representative sections of all major The adult dentition of cat CT17, which was treated for 12 weeks with GC376 starting at 4.4 months of age. There is retention of the upper left deciduous canine. The upper second and third premolars appear to be deciduous. Small permanent third premolars have partially erupted lingual to the deciduous third upper premolars. The gingiva surrounding the retained canine and premolars is inflamed. The adult canines also appear smaller than normal. The permanent right canine and fourth upper premolars appear to have erupted normally abdominal and thoracic organs, brain and eye. Gross examination identified three distinct presentations. Five cats had no gross evidence of active FIP (CT01, CT02, CT05, CT08, C12), three had lesions consistent with noneffusive FIP (CT07, CT10, CT13) and four had effusive peritonitis with multiorgan involvement (CT03, CT14, CT16, CT22). Histology of the five cats lacking gross evidence of disease demonstrated mostly mild mononuclear infiltrates, usually perivascular inflammation in the eye, liver, intestinal wall and kidney. The three cats with noneffusive FIP had mild-to-severe inflammation in many organs with the most severe lesions occurring in the eye, mesenteric lymph nodes, kidney and lung. The three cats with effusive FIP had severe pyogranulomatous inflammation in multiple abdominal organs including the omentum, peritoneum, intestinal wall, mesenteric lymph nodes, liver and spleen.