Haemangiosarcoma of the interventricular septum in a dog

UNLABELLED: Abstract CASE HISTORY: A 5-year-old male neutered Labrador Retriever Afghan crossbred dog was examined after collapsing. The dog was recumbent, dyspnoeic and mildly tachypnoeic. There was a tachyarrhythmia (300 beats per minute) and subcutaneous oedema of the ventral neck and right forelimb. CLINICAL FINDINGS: The dog had a sustained ventricular tachycardia originating in the right ventricle and on echocardiography a mass was identified in the interventricular septum. Due to the poor prognosis the owners agreed to euthanasia of the dog. PATHOLOGICAL FINDINGS: A reddish-grey mass was found in the interventricular septum and smaller red foci found scattered throughout the myocardium. There was a single, raised, splenic nodule with several smaller red foci within the splenic parenchyma. Hepatic congestion, pancreatic oedema, ascites and subcutaneous oedema of the right forelimb and neck were present. Sections of the splenic nodule, interventricular septal mass and both ventricular-free walls showed neoplastic mesenchymal cells. DIAGNOSIS: Haemangiosarcoma of the myocardium and spleen with right-sided congestive heart failure. CLINICAL RELEVANCE: This case report describes an atypical location for haemangiosarcoma. The investigation supports the use of echocardiography as a component of the protocol for staging haemangiosarcoma even in the absence of apericardial effusion. It also provides further evidence for the inclusion of intracardiac neoplasia as a differential diagnosis for dogs with unexplained cardiac arrhythmias.