7 Types of Dog Cancer and Their Severity

Fact checked by Alexandra KayReviewed by Juliane Evans

Cancer is unfortunately common in dogs. Like humans, several different types of cancer affect dogs. Some are more aggressive than others, but all require veterinary attention.

Each type of cancer affects dogs differently and many can spread to other parts of the body. The earlier cancer can be detected, the better the chances of successful treatment. Cancer treatment options depend on the type of cancer, its location in the body, and the stage of cancer (how much it has spread, or metastasized, throughout the body).

Learn about some of the most common types of cancer in dogs and how serious they are.

13 Signs of Cancer in Dogs

Malignant Lymphoma

Malignant lymphoma is one of the most common types of cancer that affects dogs. Lymphoma is a type of cancer that affects the lymphatic system. There are several types of lymphoma, and some are more aggressive than others. Many dogs will have enlarged lymph nodes in one or more parts of the body. Lymphoma may also cause changes to the eyes and internal organs.

Lymphoma can affect any dog, but certain dog breeds seem to have a genetic predisposition, including Bernese mountain dogs, Boxers, Bulldogs, Bullmastiffs, Gordon setters, and Scottish Terriers.

Some forms of lymphoma respond well to specially designed chemotherapy protocols. Treatment usually involves weekly visits for chemo administration at first, then every other week visits for about six months.

Many dogs with lymphoma will go into remission during chemotherapy, enabling them to maintain a good quality of life for longer.

Osteosarcoma

Osteosarcoma is the most common type of bone cancer that occurs in dogs. It begins as a tumor that often affects the long bones of the limbs, but it can affect any bones in the body. Osteosarcoma is an aggressive type of cancer that tends to spread rapidly, especially to the lungs, lymph nodes, and other bones.

Treatment for osteosarcoma generally involves amputation of the affected limb followed by chemotherapy. Radiation therapy may be recommended in some cases. Even with treatment, cancer can recur. Sadly, most dogs will not survive more than two years after diagnosis, even with the best treatment.

Osteosarcoma can affect any breed, but it is more common in giant dogs like Rottweilers and Irish Wolfhounds.

Hemangiosarcoma

Hemangiosarcoma is often considered the most aggressive dog cancer. It affects the lining of blood vessels in the body and commonly occurs in the spleen, heart, or liver. It can also appear on the skin. This aggressive cancer may not be detected until the dog experiences complications from tumor rupture or growth.

Ruptured splenic tumors lead to extreme bleeding and require emergency surgery to stop the bleeding. Unfortunately, many dogs are already in an advanced stage at the time of diagnosis.

Treatment typically involves surgery to remove or debulk the tumor, if possible, followed by chemotherapy. Survival times vary based on the severity and stage. Sadly, most dogs will not live long with hemangiosarcoma, even with treatment.

Any dog can develop hemangiosarcoma, but certain breeds may be predisposed, including Golden Retrievers and Labrador Retrievers.

Breast Cancer

Breast cancer is relatively common in dogs. Most mammary tumors tumors are carcinomas that begin as a lump on the abdomen near the dog's nipples. Multiple tumors may cause a kind of "chain" along the mammary glands. It may also cause enlargement of nearby lymph nodes.

Vets diagnose breast cancer by collecting tissue samples from the tumor via fine needle aspirate. Treatment almost always begins with surgery to remove the tumor and affected mammary gland. Your vet may recommend removing multiple mammary glands as well as the nearby lymph nodes.

Unspayed female dogs are most at risk for breast cancer. Spaying your dog will greatly reduce the risk.

Tumors, Growths, and Cysts in Dogs

Mast Cell Tumors

Mast cell tumors are among the most common type of skin tumors in dogs. Though they can occur elsewhere in the body. A mast cell tumor usually appears as a skin lump.

These tumors can appear harmless to the naked eye despite their malignancy. It's important for a vet to examine any skin growths on your dog to determine if they are harmful.

A fine needle aspirate may be done to collect cells from the growth. A pathologist can analyze the cells for the presence of malignant mast cells. After removal or biopsy of the mass, the pathologist will grade the tumor based on the microscopic findings. This grade describes the severity of cancer cells in the tumor. Grading the tumor, along with further information determines the stage of cancer, which determines the necessary follow up of chemotherapy and/or radioation.

Surgery is necessary to remove mast cell tumors. The veterinarian will attempt to remove the tumor completely to prevent metastasis. Follow up with chemotherapy and/or radiation therapy may be necessary depending on the grade of the mast cell tumor, whether or not it could be completely removed, and whether or not it has spread. Prognosis depends on how advanced the tumor is and whether or not the cancer has metastasized.

Mast cell tumors are seen in all dogs breeds and mixed-breed dogs, but Boxers, Shar-peis, and "bully-type" breeds (like American Staffordshire Terriers, Bull Terriers, and Bulldogs) are more likely to be affected.

Melanoma

Melanoma is a type of cancer associated with pigment cells called melanocytes. This cancer can affect any part of the body, but it often occurs in the oral cavity of dogs. Oral melanoma is the most common type of oral cancer seen in dogs.

Melanomas often look like darkly pigmented growths, but they can also be pink in color. Any new growth should be examined by a veterinarian. If you notice an oral growth, it's important to have it checked out right away. Melanoma can easily spread to other parts of the body.

Treatment of melanoma usually begins with surgery to remove or debulk the tumor. Chemotherapy and/or radiation may also be recommended. Some dogs with melanoma may be eligible for melanoma vaccine injections which may prevent a recurrence.

Although any dog breed can get melanoma, dogs with black spots in the mouth and on the tongue, like Chow Chows, seem to be predisposed. Miniature Schnauzers, Standard Schnauzers, and Scottish Terriers are also more commonly affected than other breeds.

Transitional Cell Carcinoma

Transitional cell carcinoma is a type of cancer that most commonly affects a dog's bladder and urethra. These tumors can cause difficulty or inability to urinate and blood in the urine.

If your dog is having urinary problems, it's essential that you take your dog to the vet for an examination. A urinalysis may point your vet in the direction of a tumor in the urinary tract. Bladder tumors may be discovered on radiographs or ultrasound. A tissue sample is needed in order to make a diagnosis of transitional cell carcinoma.

Transitional cell carcinoma often cannot be treated with surgery alone because these tumors usually occur in a part of the bladder that cannot be removed. In some cases, it may be possible for tumors to be surgically debulked. Follow-up treatment generally involves the use of medications like piroxicam or chemotherapy.

Small dog breeds like Scottish Terriers, Shetland Sheepdogs, and West Highland White Terriers are more commonly affected than other breeds.

Read Next: Bladder Cancer in Dogs

Read the original article on The Spruce Pets.