There have been many publications describing the effects of feline immunodeficiency virus (FIV) on cats. However to the present authors' knowledge this is the first report of a cat with chylous pleural and peritoneal effusion associated with FIV. The aim of the present paper is to describe the clinical signs, diagnosis by lipoprotein electrophoresis and serum lipid studies, the ultrasonographic appearance of chylous effusion and therapy.

A five-year-old spayed shorthair cat was evaluated for chylous effusion in the thorax and abdomen. The diagnosis of chylothorax was confirmed by serum and pleural fluid cholesterol:triglyceride ratios (a ratio of less than 1; 120/3403 mg/dl in pleural fluid and 147/570 mg/dl in serum) and lipoprotein electrophoresis with a great increase in proportion of chylomicron to 17.7%. Results of CBC included a marked leucocytosis (WBC 36.3 x10³µl and macrocytic-hypochromic anaemia (RBC 4.9 x 10⁶, MCV 69 fL, MCHC 22.5 g/dl). Cultures from the peritoneal fluid were negative. Thoracic and abdominal radiography showed a ground glass appearance and obscuration of the abdominal structures. Ultrasonographic examination confirmed the presence of pleural and peritoneal effusion. Electrocardiography was unremarkable and the test for heartworm antigen was negative. The cat was tested for antibodies to FIV and FeLV antigens and was found to be FIV-positive.

Treatment consisted of fluid replacement (intravenous Ringer's solution and 5 percent glucose), antibiotic (30 mg/kg amoxycillin once daily), diuretic drug (2 mg/kg frusemide once daily) and vitamin E. Conservative management included paracentesis, low-fat diet, medium-chain triglyceride supplementation. The cat was still alive at the time of writing with a suspected long-term prognosis.

Underlying causes of chylothorax and chyloperitoneum in cats are discussed, and clinical signs, diagnosis by lipoprotein electrophoresis and possible pathogenesis of the chylous effusion in association with FIV is discussed.