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A brief description


Hemangiosarcoma in dogs is a very challenging disease regularly encountered in veterinary practice. Unfortunately, this type of cancer is fairly common in dogs. Approx. 90 % of canine cancer patients die from this disease within one year of diagnosis.

Hemangiosarcoma is initially formed from cancer cells lining small blood vessels. They are predisposed to spreading rapidly to remote areas of the dog’s body. This is referred to as “metastasis”.

This cancer of the blood vessel walls can occur either:

  • inside the body cavity, ex. spleen, liver, kidney, heart.
  • on the surface of the skin (called cutaneous)
  • just under the skin (called subcutaneous or intramuscular)
  • there is also a bone form (called ocular)

Skin (dermal) hemangiosarcoma , if only the dermis (surface of the skin) is involved, can be easily removed surgically and carries an excellent chance of full recovery. However, the prognosis with subcutaneous (under the skin) and intramuscular (muscular tissue) forms are less optimistic.

Unfortunately, internal hemangiosarcoma (organs in the abdominal cavity) is almost certainly fatal. Growths that form in the spleen, heart, kidney or liver are difficult to detect until they become large enough for symptoms to be visible. Even at a microscopic level, hemangiosarcoma can spread and progress throughout the body, forming blood-filled tumors virtually anywhere. The cancerous tissue forming these masses is not as strong as ordinary tissue and can rupture when filled with blood, causing sudden and severe internal bleeding emergencies. Such an internal bleeding crisis is shown by sudden whitening of the tongue and gums, weakness and collapse.

More often than not, by the time the animal arrives at the veterinarian’s clinic, it is too late to provide any successful treatment or care.

Owners who notice any abnormalities of the skin (colour changes), lumps in the abdomen, or abnormal weakness in their pet should see a veterinarian immediately and insist on a thorough screening (blood analysis, urine analysis, biopsy, ultrasound imaging …).

Causes of hemangiosarcoma in dogs


Genetic predisposition


Excessive sun exposure (skin hemangiosarcoma) in dogs with minimal pigmentation and thin hair coats

Much more is unfortunately not known with certainty about other causes (nutrition, permanent stress, exposure to chemical substances ….?)

The actual causes of hemangiosarcoma, like the causes of most other types of cancer, are not well understood. Hemangiosarcoma can develop anywhere on the surface of a dog’s body, just under the skin or inside its internal organs. Here, hemangiosarcoma tends to occur most frequently in the heart, spleen, liver, kidney, abdominal cavity, eyes and bones. In fact, hemangiosarcoma of the heart is one of the most common cancers affecting the heart of in companion dogs.

The fact that certain breeds and sizes of dogs are predisposed to developing hemangiosarcoma strongly suggests that there is a genetic component to its cause.

Diagnosis of hemangiosarcoma in dogs


  • Dermal/skin
    : Cutaneous hemangiosarcoma
    Dermal hemangiosarcoma presents itself as bluish, black or red lumps on the skin. This condition may have a sun-exposure component, and occurs on areas with sparser hair growth. Dogs with short, white hair are at greatest risk for this type of hemangiosarcoma.
    Go immediately to see a veterinarian and insist on a thorough screening. A veterinarian will make a physical inspection of the lump and will send a sample to a laboratory for analysis.
    Hairless areas of a dog’s skin, like the belly and inner thighs, are prone to developing dermal, or cutaneous, hemangiosarcoma. Dogs with this type of hemangiosarcoma often have a history of prolonged exposure to sunlight. Dermal hemangiosarcoma usually shows up as a solitary tumour and is not as likely to spread – or to metastasize – as other types of this cancer.

  • Dermal/skin: subcutaneous and intramuscular hemangiosarcoma
    Hemangiosarcoma can also occur in the subcutaneous and/or intermuscular areas (just below the skin or on the muscles). This form of the disease is not thought to be associated with ultraviolet light exposure.

    Dogs with hemangiosarcoma of the layers just below the skin (subcutaneous), are less likely to have the cancer metastasize to other areas, if detected in an early stage, but these sarcomas still have a fair potency to do so. If there are intramuscular forms involved, the clinical course is unfortunately aggressive. So early detection of still small cancer masses is the key for a long-term control of the disease.
    Further readings:

  • Internal / visceral hemangiosarcoma
    Unfortunately, internal hemangiosarcoma is often diagnosed too late due to the sudden onset of symptoms from a ruptured tumor. However, if a tumor happens to be close to the skin it can be detected early. There are a number of ways to identify the cancer:

    The veterinarian will look for general swelling of the abdomen, and will look at the dog’s gums to see if they are pale (a simple check for internal hemorrhage). A blood analysis, urine sample analysis and medical imaging (ultrasound) of the chest and abdomen will also be requested. A biopsy of the tumor (sample of the cancer tissue) may be taken, but this must be done carefully to avoid triggering an internal bleeding crisis and seeding the tumor along the needle track.

Treatment of hemangiosarcoma in dogs


In the case of dermal (skin) - cutaneous or subcutaneous or intramuscular - hemangiosarcoma, careful surgical removal is usually a treatment recommended. If the tumor has been allowed to infiltrate the lower layers of the skin, muscle or inner organs, however, chemotherapy is often administered as well in order to delay metastasis. Surgical excision combined with chemotherapy give a good prognosis for cutaneous cancer, however is less successful for subcutaneous and intramuscular. If the tumor has either not been able to be removed due to its difficult location, or only partially, radio therapy will be recommended.

Internal hemangiosarcoma treatment depends on the extent and size of the tumors (their stage as veterinarians call it). In cases where the cancer is localized in the spleen and has not ruptured, surgical removal along with chemotherapy can give a medium survival time of between 2 and 4 months. Only 10% of dogs survive more than a year with internal hemangiosarcoma.

Complications of this cancer include:

blood clotting disorders leading to hemorrhage

intense pain if the cancer spreads to the bone

seizures or other neurological problems with brain metastasis (where the hemangiosarcoma most commonly spread its metastasis)

weakness and vomiting.

Unfortunately, depending upon the extent of local invasion of the cancer into surrounding areas, it is not always possible to remove all of the cancerous tissue. Radiation, chemotherapy and other available techniques that can be used to treat – or at least to manage - hemangiosarcoma.

While these techniques may help to prolong a dog’s life, they almost never accomplish a complete cure. This is unfortunately also true even if the tumors are removed before there is any detectable evidence that the cancer has spread.

Recovery prognosis of hemangiosarcoma in dogs


Pure dermal/skin hemangiosarcoma is survivable if the tumor is small, removed completely. No chemotherapy is recommended, only surgery.

Follow-up appointments and imaging will be needed to make sure the cancer has not spread (metastasis) or relapsed.

Cases where the tumor has spread (metastasis) carry a poor outlook.

Internal hemangiosarcoma is almost always fatal. Ruptured and bleeding tumors might be painful: either because there is a stretching of the capsule of the vessel or because of a compression of other organs due to the bleeding. Pain can mostly be managed medically, but the severity of the cancer is such that recovery is not possible, and pets often succumb to the complications of living with it.

A dog diagnosed with hemangiosarcoma deserves nurturing and kind supportive care, whether or not surgery, chemotherapy or other treatments are attempted. This might include administration of intravenous fluids to keep the dog well-hydrated. Blood transfusions may be appropriate, depending upon the particular dog’s condition. Of course, a clean, warm, safe living environment, a high-quality diet and free access to fresh water are always important to a dog’s comfort and overall well-being.

There is unfortunately no known way to prevent internal hemangiosarcoma from forming and spreading. Certainly, feeding a high-quality whole diet and having fresh water freely available can help to strengthen the immune system and thus promote a long, healthy, and hopefully disease-free life.

It is also important to have companion dogs seen by a veterinarian regularly for check-ups and vaccination boosters. Routine blood analysis, urinalysis, thorough physical examination and ultrasound examination of the abdomen, done twice a year from approximately the age of 5 years (depending on the breed and its size), can identify diseases or disorders of the kidneys, liver, spleen, adrenal glands, heart, lungs, thyroid gland and other vital organs, even before the dog’s owner sees any symptoms of illness. Early detection is one of the best ways to prevent or delay progression of the condition and improve the dog’s chances of partial or complete recovery.

These examinations can be quite costly, so make sure that you get a good insurance policy when you buy a dog.( see chapter 14)

How hemangiosarcoma affects dogs


While it is difficult to say with certainty how a dog with hemangiosarcoma is affected by its condition, reports from people with this disease, and observations of dogs, suggest that hemangiosarcoma usually causes a great deal of discomfort and pain, especially in the later stages. The exact symptoms will depend upon the site of the primary tumour (liver, spleen, heart, skin, bone, other), and where the cancer has spread. Palliative care could be an option you want to think about, to improve your dog’s quality of life during this last stage of his life. → see chapter 9

Resources and further readings:,+symptoms,+diagnosis+and+treatment&hl=fr&as_sdt=0,5&as_vis=1