Hemangiosarcomas in Dogs
Is an extremely invasive form of cancer that can be very dangerous

Hemangiosarcomas in dogs, although not well known by most owners, are considered to be fairly common as well as extremely dangerous.

They can and do affect all breeds of dogs, but some breeds seem to be more affected than others.

This very dangerous disease is also much more likely to affect older dogs and it can attack their skin, their subcutaneous tissues, as well as their spleen and heart.

All forms are considered to be very dangerous, but it they do affect your dog’s spleen or heart; it can be a life threatening situation.


Beagles eyesHemangiosarcomas in dogs attacks more than just the skin

Hemangiosarcomas in dogs is a very invasive variety of cancer but it much different than most forms of cancer.

The reason for this is simple; it is a blood fed sarcoma and the blood vessels go directly into the tumor.

Most affected dogs with show very few actual symptoms until this blood filled tumor becomes large.

Once it is large in size, it will in most cases also metastasized and begin to spread.

The real danger with this form of cancer is that it can also easily rupture, which in turn causes excessive bleeding in your dog.

All breeds are affected by this very invasive form of cancer, but for some reason, it seems to attack Boxers, German Shepherds, as well as Golden Retrievers much more frequently.

In the vast majority of cases, you will never know that your dog has this cancer until they have collapsed and are bleeding profusely.

Once this occurs, regardless of where it is located, it is considered an emergency.


The Skin

One of hemangiosarcomas in dog’s most frequent areas of attack is in your dog’s skin, where it will first appear as a raised growth that is either red or black in color.

This coloration is associated with the blood that is feeding into it.

In some instances, it may be caused by an over exposure to ultraviolet rays and this will affect your dog in areas where they have the least amount of hair.

This will include their abdomen or any other area where their fur coat is very short.

What makes this variety of cancer so dangerous is that these hemangiosarcomas can very easily metastasis from other tumors, and as a result, they can spread very quickly.

Complicating this condition even further is the actual identification process which has only one reliable method of positive identification; a histopathology.

Because of this, it can easily go unnoticed until it ruptures and starts to bleed.

If you do suspect that your dog has this form of cancer in their skin, you need to seek immediate medical attention.

Your veterinarian will than test the growth with what is referred to as a histopathology, which is a very simple test by removing some of the tissue and examining it under a microscope.

Once it is properly identified, it can be treated.

Treatment will involve surgical removal of the tumor as well as a very wide area of normal tissue that surrounds it.

However this can be extremely difficult only because it is very hard to know where it starts and finishes in the skin.

If it has not gone under your dog’s skin, they have a very good chance of surviving.


Subcutaneous hemangiosarcomas in dogs is considered more of a threat than the skin form, for one very simple reason; it has gone under the skin.

The early warning signs if it is under the skin will be the appearance of a lump.

This can be very deceiving as the skin that is over the lump looks perfectly normal, however, any lump in your dog needs immediate attention.

Once this is identified as hemangiosarcomas, it will also have to be surgically removed, and again will involve wide areas of surrounding tissue.

With this form however, chemotherapy is also recommended, as well as a detailed chest x-ray.

The reason for this is this form can spread very rapidly to other areas of your dog’s body as it is estimated that roughly seventy percent of all hemangiosarcomas in dogs under the skin metastasize or spread.

The Spleen

Hemangiosarcomas in dogs can also attack the spleen, where it is referred to as splenetic hemangiosarcomas.

If it affects the spleen of your dog, the only symptom you may see is one that will be very frightening; your dog collapsing.

What has happened is that there has been a sudden loss of blood because of the tumors rupturing and the blood has gone into your dog’s abdomen, forcing the sudden collapse.

If this does occur, very quickly check their gums and mucous membranes; if they are pale, something is very wrong.

If your dog’s spleen has been attacked, the entire spleen will have to be removed.

Surgery as well as chemotherapy are the only alternatives.

It is estimated that about 25 percent of all dogs that have splenetic hemangiosarcomas will also develop them in their heart.

However, the outcome here is much bleaker, as most dogs with this form of do not survive longer than three to four months, even with chemotherapy.

The Heart

The final and most dangerous attack of hemangiosarcomas in dogs is in their heart.

The signs that your will see with this form is a very sudden difficulty in breathing, fainting, collapse, or sadly, a very sudden death.

This is caused by the rupturing of the tumor or tumors and the blood is released into areas between their heart and the pericardium.

The pericardium is a very tough capsule like structure that surrounds your dog heart, and when it fills with blood, it places pressure on their heart.

Once this pressure occurs, it is unable to fill with blood, and as a result, it cannot pump properly.

The only effective treatment in this case is for your veterinarian to place a needle directly into the pericardium in an attempt to draw the blood off in order for the heart to pump the flow of blood again throughout their body.

Surgery can be performed, but it is both very difficult at this point, as well as very expensive.

Even if it is done properly, your dog may only live another four to six months in the best of scenarios.


Hemangiosarcomas in dogs, although it is not a well-known form of cancer, is a lot more common than most owners realize.

This is very dangerous form of cancer that is very aggressive and can spread rapidly.

In most all cases, except for the heart form, early detection and treatment is the only chance your dog has of surviving even with surgery and chemotherapy.


Kitchell, BE. Hope for hemangiosarcoma--Biology based treatment options. Proceedings of the World Veterinary Conference 2008.

Pet Medications for Hemangiosarcomas in Dogs

Dog Vitamin Store

Return to Lymphoma in Dogs