Diagnostic methods for achieving an antemortem diagnosis of feline infectious peritonitis (FIP)

"Tomten", a young adult male castrated orange tabby cat, presented to the Cornell University Small Animal Clinic in August, 1994, with a one week history of non-specific signs of lethargy, anorexia and weight loss, and episodes of sneezing and vomiting. Physical examination revealed a lethargic, thin, febrile cat, approximately 8% dehydrated, with palpable fluid in the abdomen and an upper respiratory wheeze originating from the left nasal passage and most audible on inspiration. A hemogram revealed: mild normocytic, normochromic, non-regenerative anemia, mature neutrophilia with a left shift and toxic changes in neurophils, lymphopenia, and eosinopenia. Total protein was within reference range. Abdominocentesis revealed a moderate amount of highly viscous, pinkish-yellow effusion with characteristics of an exudate (total protein=4.8 mg/dl; low cellularity consisting mainly of macrophages, with some neutrophils, and a few lymphocytes) that had a distinct basophilic background when viewed under high power. Serology revealed a positive FIP titer at 1:129 dilution and a positive FeLV antigen test. A diagnosis of feline infectious peritonitis was given based on clinical findings, peritoneal fluid evaluation, and serology. After 24 hours of ICU hospitalization for rehydration and systemic antibiotic treatment, the owner elected to bring Tomten home to enjoy his last few days, after which he was euthanized due to the poor prognosis for FIP