Chylothorax and Thymic Lymphoma in a Pet Rabbit (Oryctolagus cuniculus)

A 6-year-old dwarf rabbit (Oryctolagus cuniculus) presented for chronic epiphora and tachypnea. Results of a complete blood count were unremarkable, and a plasma biochemical profile revealed elevated concentrations of blood glucose and alkaline phosphatase and decreased globulin and potassium levels. Thoracic radiography showed a mediastinal mass and significant pleural effusion. Thoracocentesis revealed a chylous effusion, which was confirmed with laboratory testing. Thoracic ultrasonography confirmed the presence of the mass, and fine-needle aspirates were obtained. The final diagnosis was thymic lymphoma and resulting chylothorax. Chylothorax should be considered in the differential diagnosis for rabbits with pleural effusion. Although it is a rare condition in rabbits, chylothorax likely occurs for the same reasons as in dogs and cats.