Haemangiosarcoma

Haemangiosarcoma is a form of cancer which is becoming increasingly more common in dogs, and more so in certain breeds of dogs including German Shepherds and Golden Retrievers. Dogs with haemangiosarcoma rarely show clinical signs until the tumour has become very large and has metastasized. Typically, clinical signs are due to hypovolaemia after the tumor ruptures, causing extensive bleeding.

Owners of the affected dogs often discover that the dog has haemangiosarcoma only after the dog collapses. The tumour most often appears on the spleen, right heart base, or liver, although varieties also appear on the skin or in other locations. It is the most common tumour of the heart, and occurs in the right atrium. Here it can cause right-sided heart failure, arrhythmias, pericardial effusion, and cardiac tamponade. Haemangiosarcoma of the spleen or liver is the most common tumour to cause haemorrhage in the abdomen. Haemangiosarcoma of the skin usually appears as a small red or bluish-black lump. It can also occur under the skin. It is suspected that in the skin, haemangiosarcoma is caused by sun exposure. Occasionally, haemangiosarcoma of the skin can be a metastasis from visceral haemangiosarcoma. Other sites the tumour may occur include bone, the kidney, the bladder, muscle, the mouth, and the central nervous system.

Clinical features
Presenting complaints and clinical signs are usually related to the site of origin of the primary tumour or to the presence of metastases, spontaneous tumour rupture, coagulopathies, or cardiac arrhythmias. More than 50% of patients are presented because of acute collapse after spontaneous rupture of the primary tumour or its metastases. Some episodes of collapse are a result of ventricular arrhythmias, which are relatively common in dogs with splenic or cardiac HSA. Most common clinical signs of visceral haemangiosarcoma include loss of appetite, arrhythmias, weight loss, weakness, lethargy, collapse, pale mucous membranes, and/or sudden death. An enlarged abdomen is often seen due to hemorrhage. Metastasis is most commonly to the liver, omentum, lungs, or brain.

Treatment
Treatment includes chemotherapy and, where practical, removal of the tumour with the affected organ, such as with a splenectomy. Splenectomy alone gives an average survival time of 1-3 months. The addition of chemotherapy, primarily consisting of the drug doxorubicin, alone or in combination with other drugs, can increase the average survival time to 5-7 months. Visceral haemangiosarcoma is usually fatal even with treatment, and usually within weeks or, at best, months. In the skin, it can be cured in most cases with complete surgical removal as long as there is not visceral involvement.
Prognosis in cases of haemangiosarcoma is generally very poor.