Hemoperitoneum in a dog with cranial mediastinal lymphoma

A 2-year-old neutered male terrier-mix dog was presented to a multispecialty hospital because of acute onset of lethargy and a single episode of vomiting. The dog was unstable on admission and had a moderate hemoperitoneum as determined by point-of-care ultrasonography. Additional diagnostic tests revealed a cranial mediastinal mass and scant pleural effusion. After the dog was stabilized, a computed tomographic scan confirmed a cranial mediastinal mass with bicavitary effusion as well as bicavitary lymphadenopathy. Cytologic examination of thoracic fluid was most consistent with intermediate- to large-cell lymphoma. The dog was treated with a single glucocorticoid injection, a single administration of L-asparaginase, and oral glucocorticoid therapy that was tapered to discontinuation. The dog was presented deceased on arrival at 38 d after the initial presentation to the specialty hospital. This case report describes an uncommon differential diagnosis to consider in cases of hemoperitoneum. Key clinical message: Hemoperitoneum may occur secondary to non-intra-abdominal disease, such as mediastinal lymphoma, and a complete systemic workup should be completed.