BACKGROUND Splenic venous thrombosis (SVT) is usually considered an incidental finding on abdominal ultrasound examination but can indicate the presence of underlying disease. Concurrent disease processes and conditions in dogs with SVT have not been identified previously. OBJECTIVES To identify concurrent diseases and conditions in dogs with SVT. ANIMALS Eighty dogs with SVT. METHODS Retrospective review. Medical records from 1994 through 2008 were searched for dogs with SVT identified by ultrasound examination. These records were then reviewed for signalment, medical history, clinicopathologic testing, diagnostic imaging, and clinical diagnosis. RESULTS The most common concurrent conditions were neoplasia (54%), exogenous corticosteroid administration (43%), systemic inflammatory response syndrome (26%), disseminated intravascular coagulation (20%), pancreatitis (18%), and immune-mediated disease (16%). The most common neoplastic disease was lymphoma, and the most common immune-mediated disease was immune-mediated hemolytic anemia. Protein-losing nephropathy and naturally occurring hyperadrenocorticism were identified in <10% of the dogs. Concurrent splenic infarcts were identified in 33% of dogs, and concurrent portal vein thrombi were found in 18% of dogs. CONCLUSIONS SVT is a sonographic finding of clinical importance, and dogs with SVT can have 1 or more coexisting diseases.