Spontaneous haemoabdomen due to a ruptured primary splenic mast cell tumour in a dog

A 14-year-old, female, spayed warren hound presented with an acute history of collapse, pale mucous membranes and abdominal distension. Abdominal ultrasound and abdominocentesis revealed a haemoabdomen secondary to a ruptured splenic mass. The dog underwent an emergency splenectomy and splenic histopathology, including toluidine blue staining, was consistent with a mast cell tumour. The dog was diagnosed with a primary splenic mast cell tumour based on the absence of a primary mast cell tumour in another location at the time of presentation or in a review of the dog's medical record. Following surgery, staging identified hepatic infiltration, and adjuvant chemotherapy with vinblastine and prednisolone was started. The dog was euthanased 97 days after surgery due to progressive disease and recurrence of the haemoabdomen. Visceral mast cell tumours should be considered as an uncommon differential diagnosis in dogs presenting with haemoabdomen due to a ruptured splenic mass.