Posted in Health

Cancer in dogs

“Cancer” is probably the scariest word that could come out of your veterinarian’s mouth in relation to your dog. Hopefully you never have to face that potential diagnosis with your dog, but you should know that many types of cancer that we deal with in canines are treatable, and even completely curable. Here’s a summary of the 5 most common canine cancers, and how we deal with them.


A hemangiosarcoma is a tumor that grows from blood vessels. It can be seen on the skin, but most commonly it grows on internal organs that have very robust blood supplies, most commonly the spleen, but also the heart and liver. These tumors are filled with blood vessels and are prone to rupturing and bleeding into the abdomen, chest, or even into the sack that surrounds the heart, the pericardium. Blood loss can be so severe and rapid that it’s life threatening. Bleeding into the pericardium essentially renders the heart incapable of pumping effectively, and without immediate emergency intervention, these dogs die.

Hemangiosarcomas are more common in large breed dogs, such as Golden Retrievers and German Shepherds, but they can happen in any breed, and in mixed breeds. It’s important to know that not all bleeding tumors discovered on the spleen are cancerous. Hemangiomas are benign tumors that can grow quite big, and can also bleed into the abdomen, but don’t metastasize throughout the body like hemangiosarcomas. If your veterinarian discovers a mass on your dog’s spleen, surgery can be performed to remove the spleen, and if the mass is non-cancerous, the problem is taken care of.

Mast cell tumor

Mast cell tumors most typically grow on the skin of dogs – in fact, they’re the most common type of skin tumor seen in dogs. They are often called “the great pretender” by veterinary oncologists, because one mast cell tumor can look completely different from another. This is one reason that if you go to PetCoach asking about a suspicious lump on your dog, we will almost always tell you to go get it checked out, because it’s nearly impossible to tell whether a growth is dangerous just by looking at it.

These are tumors of a specific type of white blood cell, and they almost always appear as an innocent looking bump under the skin. Mast cell tumors are malignant, and they can spread to other parts of the body. But if we find and diagnose them in time, removing them surgically cures the problem. They can be difficult to deal with if they are on parts of the body that make adequate removal challenging, like the paw, because completely removing these tumors involves taking quite a bit of apparently healthy tissue as well.

One of the hallmarks of mast cell tumors is that they change size, sometimes even disappearing completely, only to return again. This is another reason why it’s always important to get any lump checked out as soon as possible. If you’re worried you might not be able to find it when you go to the veterinarian, it’s OK to take a non-toxic marker and circle the location directly on your dog’s fur!


Lymphoma, or lymphosarcoma, is a common type of cancer in both dogs and people. In fact, many advances in the treatment of this disease in people are due to the initial study of those treatments in canines. Lymphoma is probably the cancer that veterinarians have the most experience treating, and there are many possible treatment options for this disease.

Most of the time lymph node enlargement is detected by owners when they see or feel large lumps on their dogs that weren’t there a day or two previously. In the early stages of the disease, these dogs act totally normally. When we discover lymphoma at this early stage, we have a much better chance of successfully getting the dog into remission for a long period of time – years, even. Yet again, here’s another great reason to get your dog right in when you notice an odd lump or bump, so that an accurate diagnosis can be made and appropriate therapy started.


If you’re talking about a bump you find on your dog talk to one of the vets on PetCoach, one of the questions they might ask is whether you can grasp the entire bump in your hand, and whether the mass is attached to the tissue underneath. Fibrosarcomas are tumors that aggressively grow into the underlying tissue, making them one of the most difficult cancers to treat, even though they tend to spread to other parts of the body very slowly, or not at all.

If your veterinarian suspects your dog has a fibrosarcoma, he will likely suggest first taking a small piece of the mass off and sending it to a pathologist to confirm the diagnosis. This is called a biopsy, and it’s important in the case of a fibrosarcoma, because not removing the absolute entirety of these tumors ensures that they will grow back. Often they occur on the limbs, and so sometimes the best treatment option is complete amputation. They also respond well to radiation therapy, which is becoming more widely available for pets, at veterinary schools and specialty centers.


Melanomas are another type of cancer that is frequently a problem for humans as well as for dogs. These tumors are common in the oral cavity and on the toes of dogs, and they tend to be quite malignant and aggressively spread to other parts of the body, especially the lungs. Often melanomas are black in color, because they arise from the cells that produce melanin, the black pigment in the skin, but this isn’t universally true.

Melanomas require surgery for removal, and because of their location (mouth and feet) completely removing the entire tumor is often problematic, as too much healthy tissue may need to be removed as well. Like fibrosarcomas, these tumors do respond to radiation therapy, but since they tend to spread throughout the body, radiation may not be effective in stopping the spread of disease.

Well I hope this helps everyone. Cancer is a very hard thing to learn about from a vet or from our doctor as well. Best thing to do is explore all options of treatment and live life to the fullest. If you can tell your dog is going down hill fast and they don’t have much time left, make his/her last days amazing then let them go before they suffer to much. I know it is one of the hardest in the world to do but it is the right thing.

If you ever have any questions or just want to talk about cancer feel free to email me



I am a down home Country Woman, and I love to train dogs, and horses. I have produced my own training curriculum through my years. The following blog posts are all my beliefs and how I like to train. If you ever have questions or comments that you would like to email me directly please feel free to email me at

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