Diagnosis of systemic lupus erythematosus in a dog with an atypical presentation of pleuritis

A 3-year-old labradoodle presented with prior history of generalised seizures and had recently developed acute pyrexia and shifting leg lameness, with joint effusions in several joints. The dog also later developed pleuritis with an exudative pleural effusion. Cytological findings for all joint effusions were consistent with immune-mediated polyarthritis. Suspected lupus erythematosus cells were seen in the joints and pleural fluid, which were confirmed with Feulgen staining. Together with a positive antinuclear antibody titre, the dog was diagnosed with systemic lupus erythematosus, which responded to immunosuppressive doses of prednisolone. This case report describes the insidious nature of systemic lupus erythematosus, a rare disease that can imitate many different conditions. It is also the first reported case of lupus erythematosus cells in pleural effusion in veterinary medicine, highlighting the importance of lupus erythematosus cells as a valuable diagnostic aid to further support the diagnosis of systemic lupus erythematosus and enable early treatment to be initiated.