Dogs are always susceptible when it comes to cancer and it may be difficult to notice, especially when you are not careful. Hemangiosarcoma, or HAS, is a type of cancer that affects dogs in most instances. Cancer usually develops in the endothelial cells (cells that form in the blood vessels) forming an aggressive and infectious tumor in the area that it affects, except in cases where it affects the skin. Since cancer develops in cells that form part of the blood vessels, the tumors that develop as a result are always filled with blood.

When the tumor ruptures there can be internal bleeding in the affected area, which can lead to further complications. In critical situations, it may even result in the death of the dog. In most cases the disease is incurable and the end result, especially in cases where the cancer is discovered in its late stages, is death. An early diagnosis can help the chances of the dog living longer.

Hemangiosarcoma can occur in different organs including the skin. The most common organs that are affected include the spleen, the liver, and the tongue. The most affected organ is usually the liver or the spleen. The disease may even spread to other areas of the body such as the brain, heart, lungs, skeletal muscles, or even the kidneys.

Dogs that are middle-aged and particular breeds are more susceptible to the disease, regardless of sex. Some specific types of dogs that are more likely to contract the disease include German Shepards, Skye Terriers, Portuguese Water Dogs, and Golden Retrievers. The classification of the cancer is dependent on the particular area that it affects. The cancer is classified into dermal, hypodermal, subcutaneous, and visceral. Subcutaneous being the least aggressive and visceral being the most aggressive.

Dermal (Cutaneous) Hemangiosarcoma – Skin

Dermal (Cutaneous) Hemangiosarcoma – Skin

This type of sarcoma occurs in the skin, especially around the abdomen, and can be easily treated. Diagnosis is significant in determining the extent of cancer, as it may affect more than the epidermis. Although in most cases, cancer does not reach the dermis tissue. With the malignant nature of cancer, it may spread to other organs. Early treatment can end cancer. If your dog has this type of cancer, you will notice black or even rosy red growth on the skin of the dog. Dermal Hemangiosarcoma is usually associated with dogs being exposed to excessive sun and may occur on areas that have minimal or no hair like the abdomen. Areas that have white fur may also be affected. This implies that dogs that have short fur, like Dalmatians, for instance, are more susceptible.

However, it’s important to carry out further tests if you believe your dog may have developed this type of cancer, rather than deciding immediately to start treatment for the dog. Further tests, as stated above, will inform you of the extent of the disease’s effect and the best measures to take.

Subcutaneous (hypedermal) Hemangiosarcoma – Under the Skin

Subcutaneous is more complex than the dermal since it is more aggressive. Unlike in cutaneous cases, local control can be difficult since the lesion will appear extensive. This type of sarcoma will be notable by a dark red blood growth below the skin. More than 55% of hypedermal sarcoma is internal. If your dog has this type of cancer, it can cause bleeding that results in a mass of swelling that you may notice under the skin.

Identifying the lesion and removing it may be simple in some cases, although in others, the vet may not be able to confirm the extent of the tumor and complications may arise if the entire tumor is not removed. If you are lucky and the tumor is successfully removed, then the process should be followed by successive chromatography and some form of angiogenic therapy.

Visceral Hemangiosarcoma – Spleen

Visceral Hemangiosarcoma - Spleen

This type of sarcoma affects the spleen, a large and essential abdominal organ that plays a significant role in lymph and blood functions. Sarcoma of the spleen is dangerous as it has a tendency of bursting and profusely bleeding regardless of whether it has started spreading or not. If diagnosed early, the sarcoma can be treated by removing the spleen through an operation known as a splenectomy.

On the other hand, you may not be able to tell whether it has spread to other organs, which makes subsequent check-ups significant. Your vet can perform further surgery before removing the spleen to understand if, and to what extent, the sarcoma has spread. A study indicates that 25% of dogs that have been diagnosed with this type of sarcoma also have heart-based hemangiosarcoma.

Visceral Hemangiosarcoma – Heart

Visceral Hemangiosarcoma – Heart

Visceral Hemangiosarcoma is heart-based sarcoma that is life-threatening. When your dog has visceral Hemangiosarcoma, the blood fills the enclosure of the heart known as the pericardium. The process continues until there is no space to allow the heart to fill with blood during pumping. The condition is known as pericardial effusion and it is necessary to treat it before further complications occur. In severe cases, the Hemangiosarcoma will result in the death of the dog.

Early diagnosis can be vital in such instances, and just as in other types of Hemangiosarcoma, you should ensure that you carry out further tests to determine whether or not it has spread to other organs.


Hemangiosarcoma Causes

As noted above, dermal Hemangiosarcoma has a well-known cause. The causes of other types of Hemangiosarcoma are not as well-known and more research is still being carried out. However, since Hemangiosarcoma is common it is closely related to genetic links. In humans, the disease can be caused when one is exposed to particular chemicals like vinyl chloride. The less substantive research that has been carried out is associated with instances of the disease affecting humans.

Risk Factors

Hemangiosarcoma Risk Factors

Dogs are more susceptible than any other species to contracting the disease. In most cases, it affects middle-aged and older dogs. In some instances, however, there have been reports of dogs less than a year old being affected. Additionally, the above-mentioned dog breeds always have a higher chance of contracting the disease than other breeds. Cancer is not restricted to particular areas of the body or organs. In fact, as long as there are blood vessels in an organ, then it is susceptible to cancer development in that organ.


Hemangiosarcoma Symptoms

It may be difficult to notice the symptoms of Hemangiosarcoma since in most cases it affects the internal organs. Cancer mimics a benign tumor, so you may notice some changes in your dog’s behavior. A rupture can occur without any warning and the symptoms may be noticed depending on the location of the tumor or the organ affected.

The dermal sarcoma can easily be noticed because you only need to pay attention to the skin of your dog to notice a lump. Bone and rib tumors can cause discomfort and may be identified by a firm swelling that occurs in the affected area.

You may also notice nosebleeds, extreme weakness, pale gums, adnominal swelling, difficulty in breathing, seizures, collapsing, depression, abnormal heart rhythms, and an inability to clot blood. Additionally, you may also notice unusual weight gain in your dog that occurs because of the internal bleeding that takes place in the organs.

In Visceral Hemangiosarcoma (spleen) the tumor tends to rupture faster, regardless of the size, and bleeding occurs in the abdomen which can lead to extreme fatigue or anemia. If the bleeding is severe, then the dog may collapse. Gums in the dog’s mouth may appear white or just pale. It is important to note that in the majority of dogs the diagnosis is made when the tumor has already ruptured and has likely spread to other organs.

Hemangiosarcoma located in the heart can be noticed by observing the breathing patterns of the dog. In most cases, you will notice that the dog has difficulty breathing, and in severe instances, the dog may collapse. Fluid may also build up in the abdomen as a result of blood filling up the pericardium after the rupture, and the dog will exhibit problems when it comes to exercising.


Hemangiosarcoma Diagnosis

During diagnosis, the vet will begin with observations such as checking mucus for signs of anemia, feeling the abdomen for any instances of abdominal swelling, drawing blood to see if there is clotting and aspirating fluid from the abdomen to check if blood is present. After the first observation, the vet will move further and check blood count, urinalysis, chemistry panel, and radiograph the organs that may be affected. For a definitive diagnosis to be accomplished there has to be a biopsy or removal of the tumor, although this might be difficult depending on the location of the tumor and death may occur in the process.


Treatment of cancer can be achieved through surgical removal of the tumor. In other instances, it can be difficult to treat it, especially when the tumor occurs in the internal organs. If the entire tumor is not removed, the vet will have to continue performing chromatography on the dog until the dog recovers. In addition, it is important to note that for dermal hemangiosarcoma, radiation can be used as a means of treatment.

In cases where cancer affects the heart or spleen a more aggressive treatment will be required, although you can never be guaranteed whether it will help or not. You might get lucky if the tumor is diagnosed when it is still developing. In cases where it affects the heart, a pericardial tap may be necessary to remove the built-up fluid around the pericardial sac.

Since tumors that develop because of this cancer are malignant surgery alone may not help. For proper treatment, your vet needs to combine surgery and chromatography. Some of the common drugs offered during the treatment include Cyclophosphamide, Doxorubicin, Vincristine, and Cytoxan. Chromatography and surgery can also be combined with radiation treatment. If there is a successful treatment, then the dog might even live longer.


You can never be certain whether the dog will be cured, and for this reason, the long-term prognosis tends to be very poor. Dogs that have been treated with surgery of the internal organs can live up to two months, while dogs that are under chromatography and have a minimal tumor with no proof of the disease spreading can live up to 6 to 10 months. If you notice that your dog has metastasis it does not mean that you have to treat it with surgery alone. Besides surgery, you can include chromatography as a form of treatment that may prolong the dog’s life.

Complicated cases occur when cancer attacks the internal organs of the dog. If a cancerous spleen is surgically removed before it ruptures, the dog may survive up to 19 to 83 days, but in severe cases where the diagnosis is made after the rupture, the dog will have a shorter and unpredictable lifespan.

Cancer can cause sudden death due to a blood disorder that uses up all the clotting elements inside the vessels. Disseminated Intravascular Coagulation (DCI), the blood disorder, leads to inappropriate clotting causing platelet deficiency and consequently speeding up the death of the dog.

Bottom – line

It may be difficult to tell whether your dog is suffering from Hemangiosarcoma. You should not, however, assume that the above symptoms only imply that your dog has hemangiosarcoma. You should ensure that your vet carries out an extensive examination so that you can be certain you start the appropriate treatment process. In addition, it is important to visit the vet for a regular checkup and to strictly follow the prescriptions given.