New therapies under investigation for cardiac hemangiosarcoma, a devastating cancer in dogs
Cancers originating in the heart are rare in the dog, representing only 0.19 percent of all cancers. Cardiac hemangiosarcoma is by far the most common, accounting for 70 percent of primary heart tumors.
Hemangiosarcoma arises from the cells associated with blood vessels. As expected, the heart has a rich blood supply, making it a logical location for hemangiosarcoma to develop. Most cardiac hemangiosarcomas occur in the right atrium and auricle. These tumors are most common in middle-aged to older dogs, and many studies cite golden retrievers and German shepherd dogs as the most common breeds for cardiac hemangiosarcoma.
The clinical signs associated with cardiac hemangiosarcomas can be vague, and include poor appetite, lethargy, weakness and collapse. We know that hemangiosarcomas bleed, sometimes intermittently but often suddenly and profusely. Because the heart is surrounded by a pericardial sac, blood fills the sac, compressing the heart. Sometimes this compression can act like a pressure bandage, slowing bleeding. However, the compression compromises heart function. Blood in the pericardial sac muffles normal heart sounds and causes pulses to be weak, two abnormalities that veterinarians can detect on physical examination.
The majority of cardiac hemangiosarcomas are diagnosed using cardiac ultrasound (echocardiogram). Electrocardiogram changes suggesting pericardial fluid sometimes can be present, and tests can be performed on pericardial fluid to help confirm a diagnosis when echocardiogram results are not definitive. Two studies looking at dogs with hemangiosarcoma in the spleen found that approximately 9 to 25 percent also had heart tumors at the time of diagnosis. One of these same studies looked at the reverse situation, and found that in dogs with primary heart tumors, nearly one-third had signs of metastases to the spleen. The results of these studies have prompted many veterinary oncologists to recommend that both cardiac and abdominal ultrasound be considered in cases of suspected hemangiosarcoma.
Unlike spleen masses, removing a growth from the heart is a difficult procedure requiring a highly skilled surgeon. Unfortunately, even with chemotherapy and surgery, the average survival time is only five months. With surgery alone, the prognosis is even worse, with an average survival time of approximately 46 days.
Morris Animal Foundation has a long-standing commitment to finding better ways to treat and diagnose hemangiosarcoma. Given the poor prognosis for these tumors in spite of chemotherapy and surgery, innovative treatment strategies are desperately needed. One ongoing foundation-funded research project is focused on understanding what nutrient pathways are important for cancer survival. The research team’s goal is to find a pathway that is critical to tumor survival, then block the pathway. If successful, this research could provide a novel way to treat this aggressive cancer.
Learn more about our cancer research projects and how you can join us in the fight against hemangiosarcoma.