|Hemangiosarcoma in dogs is an aggressive, malignant tumor of blood vessel cells. With the exception of the skin
form of hemangiosarcoma, a diagnosis of hemangiosarcoma is serious. Because these tumors start in blood
vessels, they are frequently filled with blood and when a blood-filled tumor ruptures, it can cause problems with
internal or external bleeding.
Hemangiosarcoma can theoretically arise from any tissue where there are blood vessels, which is essentially
anywhere in the body, but usually appear in the skin, soft tissue, spleen or liver with the most common site being
the spleen. They are highly metastatic and will frequently spread to the brain, but also to the lungs, spleen, heart,
kidneys, skeletal muscle and bone. This type of cancer in dogs is typically classified as dermal, subcutaneous or
hypodermal, and visceral.
The skin form of hemangiosarcoma are the most easily removed surgically and have the greatest potential for
complete cure. The skin form looks like a rosy red or even black growth on the skin. This form is associated with
sun exposure and thus tends to form on non-haired or sparsely haired skin (such as on the abdomen) or on areas
with white fur. Dogs with short white haired fur (such as Dalmatians and pit bull terriers) are predisposed to the
development of this tumor. Approximately 1/3 of cases will spread internally in the malignant way usually associate
with cancer so it is important to remove such growths promptly. This form of menagiosarcoma is covered more
broadly in the Skin Cancer section of this website.
|The dermal form of Hemangiosarcoma in dogs is associated with sun exposure. It is uncertain what the causes are
for the other forms of this disease, but in humans exposure to certain chemicals, such as vinyl chloride has been
implicated. Because of the increased incidence in several breeds, a genetic link appears to be one of several likely
causes. Hemangiosarcoma is rarely found in humans, so less research has been done, and the amount of
information about the cause of this tumor is somewhat limited.
|Hemangiosarcoma is more common in dogs than in any other species. It usually occurs in middle-aged to older dogs
6 to 13 years of age, although it has been seen in dogs less than one year of age. It tends to develop in mid to
large size breeds and especially German shepherds, golden retrievers, labrador retrievers, Boxers, Dobermans,
and English setters.
The most common primary location of this cancer in dogs is the spleen. Other primary locations include the heart,
liver, skin, and bone; however, it can start in any location where blood vessels are present. These tumors usually
spread to the lungs, liver, spleen and heart.
|Because hemangiosarcoma tumors most often in develop in internal organs, frequently, there are few or no obvious symptoms
before the onset of severe clinical signs of disease. Signs of this disease are usually the result of the tumor rupturing, which causes
bleeding. This may occur without any warning, and the symptoms will depend upon where the tumor is located. The most common
symptom will be a lump under the skin, visible bleeding, sometimes in the form of nosebleeds, tiring easily, episodes of unexplained
weakness, pale color in the gums, difficulty breathing, abdominal swelling, seizures, abnormal heart rhythms, collapse, and
When the tumor is located in the spleen or liver, the clinical signs are usually due to rupture of the tumor and subsequent bleeding
into the abdomen. This causes anemia, weakness and if the bleeding is severe, collapse. The gums may appear to be pale or white.
In relative few dogs, the diagnosis is made before the tumor ruptures.
When the tumor is located in the heart, it can cause symptoms, such as weakness, collapse, difficulty breathing, exercise intolerance
and fluid build-up in the abdomen. This is usually due to the development of fluid around the heart, called pericardial effusion. The
pericardium is a thin sack that surrounds the heart and with hemangiosarcoma, the pericardium fills up with blood due to rupture of
When the tumor occurs in the skin, a mass or lump can usually be felt in or under the skin. The mass may become ulcerated and
bleed. When the tumor occurs in a bone, it can cause pain and discomfort. In some locations, such as a rib, the tumor can be felt as
a firm swelling in the bone.
|The treatment for hemangiosarcoma depends upon the location of the tumor. Treatment is more successful when this cancer occurs
on the skin than when it is found in an internal organ. Most dermal hemangiosarcomas can be successfully treated and cured by
surgical removal of the tumor. Chemotherapy is often used in addition to surgical excision if the veterinarian was not able to remove
the entire tumor or it has penetrated into the subcutaneous tissue or muscles below the skin. Radiation therapy is also used to treat
The visceral forms of this disease require more aggressive treatment, and even then, the treatment will not likely be curative. If a
tumor is identified when it is small, it may be possible to remove the spleen if the tumor is there or to remove tumors found near the
heart and prolong the dog’s life. A pericardial tap may be required to treat the build up of fluid around the heart or the pericardial sac
may be removed. Surgery alone will not make much difference because these are highly malignant tumors and most have spread by
the time they have been diagnosed. For this reason, combining surgery with chemotherapy is the standard treatment. Many
chemotherapy protocols exist which may include the following drugs: cyclophosphamide, vincristine, doxorubicin, and cytoxan. The
use of radiation has not been proven to be useful in fighting this disease at this time.
Treatment for the bleeding disorders and aggressive supportive care also prolong the life of patients with hemangiosarcoma.
|Hemangiosarcoma is rarely curable and long-term prognosis for dogs with hemangiosarcoma is poor. Dogs with internal organ
involvement who are treated with surgery alone live an average of only 2 months. Dogs who do not have identifiable metastasis at
the time of surgery and who are treated with chemotherapy live a median of 6 to 10 months. Some dogs with demonstrable
metastasis may also respond to chemotherapy, providing a prolonged quality of life compared with dogs that are not treated at all.
Dogs with this type of cancer located in the subcutaneous tissues (just under the skin) live a median of about 6 months with surgery
Studies have shown that surgery to remove the spleen (splenectomy), offers a median survival time of 19-83 days. Dogs with a
primary tumor of the spleen that has not ruptured, has a better prognosis. However, if the spleen has ruptured before it can be
removed, the prognosis is poorer. The combination of splenectomy and chemotherapy can increase survival time but fewer than
10% of dogs survive a more than one year.
The blood disorder that most commonly accompanies the presence of hemangiosarcoma tumors is disseminated intravascular
coagulation (DIC). This is blood clotting that is occurring inappropriately inside the blood vessels. It uses up all of the blood clotting
elements rapidly and dogs with this condition usually have platelet deficiencies, increased blood clotting times, decrease in fibrin
content in the blood and an increase in fibrin degradation products (FDPs). This may be the cause of death in many dogs affected
|In order to diagnose the potential disease, the veterinarian will begin with an examination of the dog. This may include looking at the
mucous membranes for signs of anemia (pale gums), feeling for abdominal swelling, aspirating fluid from the abdomen to see if blood
is present, and drawing blood to see if clots form. Further diagnostic work-up will most likely include a complete blood count,
chemistry panel, urinalysis and radiographs (x-rays) of the chest and abdomen to determine the extent of organ involvement and
whether metastasis is present. Definitive diagnosis is accomplished by biopsy or removal of the tumor. This can be challenging
because there may be multiple tumors and/or the primary tumor site may be difficult to determine. There is also a significant risk of
severe hemorrhage during these surgical procedures.
|Subcutaneous (hypedermal) Hemangiosarcoma
The overlying skin of a subcutaneous hemangiosarcoma is often completely normal. However below the skin is a
dark red blood growth. Up to 60% of hypodermal hemangiosarcomas spread internally
Visceral Hemangiosarcoma - spleen
The spleen is a large abdominal organ which while not essential for life, serves an important role to the blood and
lymph functions. Splenic growths have the unfortunate tendency to break open and bleed profusely regardless of
whether they are benign or malignant. While a splenectomy (removal of the spleen) ends the prospect of this type of
life-threatening sudden bleed, splenic hemangiosarcoma is still a rapidly spreading malignancy.
When a splenic mass is detected, it may not be possible to tell prior to splenectomy whether or not the mass is
malignant or not although testing will most likely be performed to attempt to determine this. It has been estimated
that 25% of dogs with splenic Hemangiosarcoma also have a heart-based Hemangiosarcoma.
Visceral Hemangiosarcoma - heart
Similar to splenic hemangiosarcoma, heart-based hemangiosarcoma tends to be life-threatening from the effects of
bleeding. The heart is enclosed in a sac called the “pericardium.” When the hemangiosarcoma bleeds, the blood
fills up the pericardium until it is so full that the heart inside is under so much pressure that it has no room to fill with
the blood it has to pump. This is called pericardial effusion and must be treated before an emergent situation
Want to help find a cure for hemangiosarcoma? If your dog has been diagnosed with this terrible disease, please click here and consider helping to find clues to it's genetic
basis, ways to diagnose the disease early and develop new and effective treatments.
Compound Derived From a Mushroom
Lengthens Survival Time in Dogs With
Cancer, Penn Vet Study Finds
September 10, 2012
PHILADELPHIA — Dogs with
hemangiosarcoma that were treated with a
compound derived from the Coriolus versicolor
mushroom had the longest survival times ever
reported for dogs with the disease. These
promising findings offer hope that the
compound may one day offer cancer patients
— human and canine alike — More..