OBJECTIVE To characterize and investigate potential associations between causes of pleural effusion and various clinical factors in a large cohort of affected cats. DESIGN Retrospective case series with nested cross-sectional study. ANIMALS 380 client-owned cats with a diagnosis of pleural effusion from January 1, 2009, through July 14, 2014, for which the cause of pleural effusion had been fully investigated. PROCEDURES Electronic medical records were reviewed and data collected regarding cat characteristics, clinical signs, cause of pleural effusion, treatment, and survival status at discharge from the hospital. Variables were examined for associations with causes of pleural effusion. RESULTS 87 (22.9%) cats died or were euthanized before discharge from the hospital. Congestive heart failure (CHF) was the most common cause (155 [40.8%]) of pleural effusion, followed by neoplasia (98 [25.8%]). Other causes included pyothorax, idiopathic chylothorax, trauma, feline infectious peritonitis, and nontraumatic diaphragmatic hernia. Cats with trauma or feline infectious peritonitis were significantly younger than those with CHF or neoplasia. Cats with lymphoma were significantly younger than those with carcinoma. Cats with CHF had a significantly lower rectal temperature at hospital admission (mean ± SD, 36.9 ± 1.2°C [98.4 ± 2.2°F]) than did cats with pleural effusion from other causes (37.9 ± 1.2°C [100.2 ± 2.2°F]). CONCLUSIONS AND CLINICAL RELEVANCE Cats with pleural effusion in this study had a poor prognosis; CHF and neoplasia were common causes. Age and hypothermia may be helpful to raise the index of suspicion for certain underlying causes of pleural effusion in cats.

Objectives To determine the proportion of dogs diagnosed with immune‐complex glomerulonephritis in a large cohort of UK dogs with clinical suspicion of glomerular disease in which renal histopathology, including routine light microscopy, transmission electron microscopy and immunofluorescence, had been performed. The second objective was to describe treatment and long‐term clinical outcome of dogs diagnosed with immune‐complex glomerulonephritis. Materials and Methods Sixty‐two UK dogs that underwent renal biopsies for investigation of suspected glomerulopathy (urine protein‐to‐creatinine ratio persistently >0.5) were included in this retrospective multicentre study. Signalment, clinico‐pathological abnormalities, histopathological diagnosis, treatment following diagnosis and survival were recorded. Results Seventeen (27%) of the dogs with suspected glomerular disease were diagnosed with immune‐complex glomerulonephritis and nine (53%) of these were still alive at the study end point, with a median follow‐up of 366 days (range 52 to 1299). Six dogs diagnosed with immune‐complex glomerulonephritis were treated with mycophenolate. Four received mycophenolate alone for immunosuppression and two received mycophenolate and chlorambucil; all these six dogs were alive at data collection [median follow‐up time 712.5 days (range 73 to 1299)]. Seven dogs diagnosed with immune‐complex glomerulonephritis did not receive immunosuppressive treatment; only one of these dogs was alive at study end point [median survival time 302 days (range 52 to 723)]. Clinical Significance Immune‐complex glomerulonephritis may be less common in the UK than previously reported in North America and mainland Europe, reducing the likelihood of treatment modification following renal biopsy. Mycophenolate was the most commonly used immunosuppressant for cases of immune‐complex glomerulonephritis.