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What is it?

Haemangiosarcoma is a very aggressive cancer (a malignant tumour) that grows from blood vessel cells (endothelium). It can affect the bone, the heart, the liver, the skin (where it is usually less aggressive, for some reason) or, most commonly, the spleen. Wherever they start, however, they tend to rapidly spread to other organs, especially abdominal organs and the lungs.

Why is it important?

The cause in dogs is unknown; however, like most tumours, it is most common in older pets and probably relates to certain genetic alterations. In humans, the disease has been associated with certain chemicals (such as arsenic), but this has NOT been proven in dogs.

What's the risk?

Although any dog may develop a haemangiosarcoma, it is most common in older dogs (the average age at diagnosis is 8-10 years). It is also most common in certain breeds - German Shepherds, Boxers and Pointers are among the breeds with the highest risk.

What happens to the pet?

To some extent, of course, the symptoms will depend on where the primary tumour has formed. However, in all cases, the cancerous mass of abnormal blood vessels is prone to leaking or even, in severe cases, rupturing, causing massive internal bleeding. In many cases, the first symptom is collapse due to severe blood loss.

Bone Haemangiosarcomasform (as one would expect!) in the bone, causing pain, lameness, unexplained breaks (a “pathological fracture”) and often local soft tissue swelling. If the affected bone is a rib, there may also be bleeding into the chest and difficulty breathing.

Heart Haemangiosarcomasare the most common form of heart cancer, and usually lead to rapid heart failure, due to pressure on the heart and bleeding into the sac around the heart (the pericardium). This causes difficulty breathing, pale gums, fast heart rate, abnormal heart rhythms, and sometimes fainting or collapse, especially after exercise.

Skin Haemangiosarcomasare less aggressive, and tend to form large “blood-blister” type lumps in or under the skin, often with local bruising.

Liver and Spleen Haemangiosarcomas are, however, the most common. Symptoms range from a swollen spleen, discovered by accident when the vet is examining your dog; to sudden collapse or even death. In most cases, there will be weight loss, weakness, intermittent collapse, pale gums, and sometimes wobbliness or lameness first.

How do you know what's going on?

In most cases, the only way to obtain a definitive diagnosis is to surgically remove part of the tumour and send it away to a veterinary pathologist to examine. This is relatively straightforward for skin masses, but for heart or large spleen or liver tumours, may not be possible. However, the presence of a tumour in these locations that contains a mass of tight blood vessels (often visible on an ultrasound scan) is very highly suspicious, and if it is obviously bleeding or leaking as well, this is usually considered diagnostic.

What can be done?

This is a very aggressive, very dangerous condition.Surgical removal of the tumour, if possible, may help; if the tumour is small, chemotherapy may also be advantageous. However, the average survival time is still very low for heart, liver or spleen tumours. Recent studies have in fact suggested that, in the case of a large tumour of the liver or spleen, there is no advantage in attempting to remove the tumour, as the survival time for dogs undergoing surgery is the same as for those who simply have palliative care. The average survival time following surgery for all except skin cases is less than 3 months. Aggressive chemotherapy may extend this, but it does depend on the size and nature of the tumour.

Skin haemangiosarcomais a less aggressive disease, however; radical surgery to remove the tumour and possibly follow up chemotherapy can be very successful, especially for tumours that are in the skin (Dermal) rather than under it.

How can I protect my pet?

Sadly, there is currently no way of preventing haemangiosarcoma.