Download Canine Hemangiosarcoma

Canine Hemangiosarcoma
By Dr. Ed Mapes
“Some days you get the bear, and sometimes the bear gets you”. Veterinary medicine is
for the most part a very rewarding profession. I manage to leave the hospital on most
days satisfied that we were able to help a number of animals, and sometimes save a life
or two – I tell our staff on those occasions that “we got the bear today”.
Dogs afflicted with hemangiosarcoma (HSA), a malignant form of cancer known to
spread aggressively, often prove to be among the most difficult cases: those that in
spite of the most diligent efforts and best techniques available, we’re unable to save an
animal. These are the depressing days when the bear gets us.
Reports estimate that anywhere from 1/2 to 2/3 of splenic masses (growths or tumors of
the spleen) are malignant tumors, and the majority of these are hemangiosarcomas
(HSA). HSA is a malignant neoplasm that arises from the inner wall of blood vessels
that is known to spread early and aggressively (Figure 1). This neoplasm can arise in
any tissue – since it originates from blood vessels – but the spleen is the most common
site of tumor development in the dog, accounting for 50 to 65% of all canine HSA. This
is also the most common tumor of the canine heart, and is also found as skin growths
These cases can be particularly heartbreaking because clinical signs in dogs are
usually very subtle – offering little warning even though the neoplasia grows and
spreads – until the dog finally develops recognizable symptoms. These dogs often
proceed from being presumably very healthy to having a diagnosis of a potentially
serious cancer the very next day.
Subtle clinical signs include weakness, increased thirst, vomiting, gradual loss of
appetite, abdominal distention, rapid heart and breathing rates, pale mucous
membranes and weight loss. If I see these symptoms in a middle aged or older dog that
is medium to larger size, I automatically include HSA in my list of possible diseases.
German shepherds are reported to be more susceptible to this tumor than most dog
breeds, but I’ve seen HSA in many breeds; recent cases have included two golden
retrievers and two Australian Shepherds.
Patients can look very much like this wonderful dog, but have a deadly cancer growing
inside.
We run tests to determine the cause of symptoms in these situations, and we proceed
accordingly if indications point toward HSA. This usually involves surgery to remove the
affected tissue and submit for biopsy.
If diagnosed early enough, we can get to the splenic tumor before it ruptures and begins
to bleed. In these cases, we search the abdominal cavity for evidence of tumor spread,
and contact the owner directly from the operating room with the results. The spleen is
removed (splenectomy) if that is the only site found. If, however, HSA has already
spread to other tissues, the prognosis is grave and a decision is made to proceed with
the splenectomy to preclude bleeding or to perform humane euthanasia at that time.
In the event that the tumor has ruptured and is bleeding, the dogs become very weak,
breathe rapidly, have pale gums, and are in a critical situation. Not every splenic tumor
that bleeds is HSA – so immediate surgery is indicated to assess the spleen, liver, and
other abdominal organs and lymph nodes to correct the bleeding and assess the degree
of tumor spread.
Benign massesmand some less aggressive tumors of the spleen afford a very favorable
prognosis, but the life expectancy for patients with splenic HSA is poor despite
aggressive surgical and drug therapy. Median survival time for splenic HSA treated with
surgery alone is only a matter of days to about three months. The addition of
chemotherapy following surgery has been reported to increase the median survival time
to 140 days to over a year. The addition of immunotherapy (L-MTP – a drug the FDA
has not approved) available only from other countries – reportedly increased survival to
a median of 273 days in one study.
Alert pet owners that notice changes in their dog’s behavior and habits, and
veterinarians that are able to make accurate diagnoses are keys to early detection and
corrective action for these patients. The prominent signs are a decrease in activity
levels and appetite, increased thirst, and weakness; be aware of these symptoms and
please contact your veterinarian to have an examination done when noticed. Early
detection and therapeutic action helps us to “get the bear”.