Infectious Disease — Feline

A young multi-cat-household cat with antibiotic-unresponsive fever and a high-protein, low-cellularity effusion with A:G ratio below 0.4 is classic effusive FIP. Septic effusions are highly cellular with degenerate neutrophils and bacteria. Severe panleukopenia with acute gastroenteritis in an unvaccinated kitten is classic feline parvovirus (panleukopenia). Salmonella can mimic it but profound leukopenia of this degree in this signalment points to panleukopenia. Retroviral status should be known for every cat before introduction to a household; a point-of-care FeLV antigen and FIV antibody test is the standard screen, with confirmatory testing for positives and retesting after the window period for recent exposures.