While there are many forms of cancer in dogs, one of the more common canine cancers is hemangiosarcoma (HSA). In fact, it is estimated that one in four dogs will be diagnosed with cancer in their lifetime, and hemangiosarcoma is listed as one form of cancer commonly seen by veterinarians, according to the Veterinary Cancer Society. hemangiosarcoma is a cancer of cells that build blood vessels. This can be a major problem for organs that have large blood vessel networks, such as the spleen, liver, and you guessed it–the heart.

Risk for the Portuguese Water Dog

As previously discussed in the cancer overview summary, cancer is an evolving disease that is hard to detect, this also means diagnosing hemangiosarcoma can be difficult. This stresses the importance of having a good, working relationship with a veterinarian you trust and one that knows your Portuguese Water Dog. If the disease is present, a veterinarian can reach an hemangiosarcoma diagnosis using a thorough history that may include changes in appetite or fluctuations in weight, unexplained bleeding episodes or weakness, and/or difficulty breathing; in combination with physical changes on examination such as subtle changes in your dog’s anatomy from swellings or even pale mucous membranes (such as their gums). Diagnosing cancer is something veterinarians do not take lightly, so they will encourage a complete work-up that may include a variety of diagnostics such as lab tests and advanced imaging.

Even though the American Animal Hospital Association (AAHA) has stated that PWD are one of the commonly affected dog breeds when it comes to hemangiosarcoma, it is becoming apparent that this cancer is a common disease that affects most dogs and is not limited to specific breeds. If you are questioning the role of your dog’s breed in the development of cancer, keep in mind that the fact your dog is a PWD does not overtly increase the odds of developing cancer in general or hemangiosarcoma in particular. Every aging dog is at risk for developing cancer and the best person to talk over your concerns with is your veterinarian.

Treatment Options and Prevention

Treatment options for hemangiosarcoma are difficult and dependent on how the disease manifests. More times than not, hemangiosarcoma is diagnosed after an emergency surgery as a result of a ruptured internal tumor (very commonly found on the spleen). While in surgery, the source of the bleeding is stopped, and the tumor and spleen are also removed. While this cancer is often terminal, 10-20% of dogs affected with hemangiosarcoma are expected to do well for months to years following removal of the spleen, especially if the surgery is followed with adjuvant chemotherapy to keep any lingering residual tumor cells at bay.

Dog owners, and in particular those who have had a previous dog affected by hemangiosarcoma, commonly ask the same question regarding prevention. That question is, should I have my dog’s spleen removed to prevent hemangiosarcoma? The answer is categorically, NO! The canine spleen is an important immune and blood-storing organ. It is not present just for show. In addition to the risks of removing a healthy spleen, because the hemangiosarcoma cells seem to originate in blood forming organs (like the bone marrow), if they can’t find a home in the spleen, they will simply go somewhere else, which in all likelihood will be harder to treat.

Perhaps a simpler option is to ask the veterinarian to have bloodwork reviewed manually by a pathologist as part of the dog’s yearly (or semiannual) health checks. There are certain characteristic abnormalities in some types of cells, such as red cells and platelets, that can clue in the pathologist to the possible presence of some forms of cancer, even before the tumor is visible. But again, this is neither sensitive nor specific. Both imaging and blood tests are routine and accessible, but neither is inexpensive.

Prognosis – After the Diagnosis

Many factors affect the mortality associated with hemangiosarcoma, none the least of which is the relative capacity of the human family members to tolerate bleeding episodes versus the decision to have the dog euthanized. The heart-wrenching decisions of whether and how to treat a dog with hemangiosarcoma are individual and what works best for one dog and their family may be very different from what works well for other dogs and their families. As mentioned above, the individual options will vary depending on the situation, so lean towards the guidance of your veterinarian; and if your dog develops hemangiosarcoma, consider allowing them to participate in legitimate, controlled clinical studies.

If you haven’t done so already, you are encouraged to read through our cancer overview article to understand this disease overall. Other articles on this website address some other forms of cancer that you may find informative.

This article has been written by Meagan Wojtysiak, Kelly Makielski, DVM, MS, DACVIM (Small Animal Internal Medicine) Animal Cancer Care and Research Program, University of Minnesota, St. Paul, MN