Efficacy and safety of the nucleoside analog GS-441524 for treatment of cats with naturally occurring feline infectious peritonitis

Pedersen, Niels C; Perron, Michel; Bannasch, Michael; Montgomery, Elizabeth; Murakami, Eisuke; Liepnieks, Molly; Liu, Hongwei

Four cats (CT56, CT62, CT72, CT75) were euthanized or died within 2-5 days of enrollment and necropsies were performed on all but cat CT75. A fifth cat (cat CT54) was euthanized after 26 days of treatment. All five of these cats presented with severe abdominal effusive disease. Cats CT54 and CT56 had evidence upon necropsy of widespread pyogranulomatous vasculitis involving the abdominal viscera, central nervous system and eyes. Cat CT56 also had compromise of the ileal wall in an area of dense infiltrate and secondary bacterial sepsis. Cat CT72 had severe pyogranulomatous vasculitis restricted to the abdomen with moderate-to-severe peripheral edema and mineralization of the adrenal cortices. Cat CT62 suffered from severe pyogranulomatous and fibrinosuppurative peritonitis, which was complicated by an acute gastric perforation associated with plant material and intralesional bacteria indicative of sepsis. Cat CT75 presented with a chronic form of FIP characterized by severe stunting of growth, a massive low protein/low cell abdominal effusion, gallop rhythm indicative of impaired cardiac function, and moderately severe peripheral edema. An echocardiogram showed bilateral atrial enlargement but no indication of primary cardiac disease. The cat appeared to respond to GS-441524 and was discharged. The cat went into shock 2 days later and was euthanized without necropsy.