Hemangiosarcoma is a malignant tumor of the blood vessel lining that typically affects older dogs between the ages of 8-13. German Shepherd Dogs and Golden Retrievers are over represented in the breed of dogs afflicted with this tumor, although it can occur in any dog. Commonly affected primary sites include the spleen, right atrium / auricle (heart), skin and subcutaneous tissues and the liver. Infrequently, other tissues like the lung, oral cavity, muscle, bone, kidneys, urinary bladder, retroperitoneum and uterus may be affected by a primary tumor.
The most common primary site for hemangiosarcoma in the dog is the spleen. There is no known cause of this tumor and it is the diagnosis in 25-50% of all splenic masses. If there is rupture of the mass and subsequent bleeding into the abdomen, it is more likely to be splenic hemangiosarcoma rather than the benign form (hemangioma or hematoma).
Classic clinical signs associated with splenic hemangiosarcoma include weakness, abdominal distension, elevated heart rate and respiratory rate, pale mucous membranes, weight loss, a history of collapse or weakness. Many dogs have several episodes of weakness that resolve within 24 hours before they become critically ill due to a very severe bleed. These clinical signs are the result of intermittent bleeding from the tumor. Less frequently dogs die suddenly as a consequence of tumor rupture and severe hemorrhage.
Unfortunately, diagnosis of hemangiosarcoma is usually made when a pet develops a severe bleed and needs to be taken to the veterinarian on emergency. At this time, free blood in the abdomen and a large splenic mass are documented. If a concerning splenic nodule is found incidentally on ultrasound when your pet is being evaluated for another problem, surgical removal of the spleen is usually recommended, as long as your pet is otherwise generally healthy. Therefore, the diagnosis of splenic hemangiosarcoma is obtained by surgical removal of the diseased spleen.
Surgery allows us to remove the tumor in order to get a definitive diagnosis on histopathology and also to evaluate the rest of the abdomen for evidence of metastasis. When these tumors metastasize, they tend to go to the other organs in the abdomen (liver, omentum, mesentery) and later to the lungs and brain. For this reason, it is recommended that all dogs with splenic masses be staged for disease elsewhere with chest x-rays, abdominal ultrasound and an echocardiogram of the heart.
Treatment and Prognosis:
The treatment of choice for splenic tumors is surgical resection of the entire spleen followed by chemotherapy.
With no treatment (no surgery), patients usually die due to a fatal bleeding secondary to tumor rupture or due to DIC (coagulation abnormalities secondary to their tumor). Chemotherapy alone (no surgery) has not been shown to be effective against this tumor as patients are still at risk for a fatal rupture of the tumor and death due to blood loss. Surgery alone has found a median survival time of 1-3 months. In this case, patients are at high risk for succumbing to metastasis to other areas in the abdomen or to the chest.
Surgery followed by chemotherapy has the longest reported a median survival time of 6 to 8 months. The current recommended chemotherapy protocol consists of a medication called Doxorubicin (Adriamycin) given every 3 weeks for a total of 5 treatments.
If metastatic disease is discovered during workup or surgical exploratory, prognosis is extremely poor as we are unable to remove all the lesions and these tumors can cause fatal bleeding at any time. Chemotherapy has limited utility in the face of gross metastatic disease and prognosis for these patients is typically weeks to a few months.
There are some newer studies looking at herbal supplements that have been effective at controlling bleeding in dogs with hemangiosarcoma as well as prolonging survival times.