7 Types of Dog Cancer and Their Severity

Young female veterinarian with a golden retriever on the exam table
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Cancer is unfortunately common in dogs. Like humans, there are a number of different types of cancer that affect dogs. Some are more serious and invasive than others, but all require veterinary attention.

Each type of cancer affects the body differently, though many of the signs of cancer can be similar at first. The earlier cancer can be detected, the better the chances of successful treatment. This is why it's so important to bring your dog to the vet for routine wellness exams. It's also important to bring your dog to the vet during the first signs of illness.

Some cancers can be treated by simply removing the cancerous tumor via surgery. Others require chemotherapy or radiation therapy. 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).

  • 01 of 07

    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, some of which are more aggressive than others. Many dogs will experience enlargement of the 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 breed of dog, but certain dog breeds seem to have a genetic predisposition, including Bernese Mountain Dog, Boxers, Bulldogs, Bullmastiffs, Gordon setter, 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 maintaining a good quality of life for longer.

  • 02 of 07


    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.

  • 03 of 07


    Hemangiosarcoma is a type of cancer that affects the lining of blood vessels in the body. It 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 breed may be predisposed, including Golden Retrievers and Labrador Retrievers.

  • 04 of 07

    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.

    Continue to 5 of 7 below.
  • 05 of 07


    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. In fact, 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.

  • 06 of 07

    Mammary Gland Carcinomas

    Breast cancer is relatively common in dogs. Most of these tumors are carcinomas. Mammary tumors 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 mammary 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 and the nearby lymph nodes.

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

  • 07 of 07

    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.

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  1. Gardner, Heather L et al. Dogs as a Model for CancerAnnual review of animal biosciences vol. 4 (2016): 199-222. doi:10.1146/annurev-animal-022114-110911

  2. Edmunds, Grace L et al. Dog breeds and body conformations with predisposition to osteosarcoma in the UK: a case-control studyCanine medicine and genetics vol. 8,1 2. 10 Mar. 2021, doi:10.1186/s40575-021-00100-7

  3. Kim, Jong-Hyuk et al. Pathobiology of Hemangiosarcoma in Dogs: Research Advances and Future PerspectivesVeterinary sciences vol. 2,4 388-405. 6 Nov. 2015, doi:10.3390/vetsci2040388

  4. Garrett, Laura D. Canine mast cell tumors: diagnosis, treatment, and prognosisVeterinary medicine (Auckland, N.Z.) vol. 5 49-58. 12 Aug. 2014, doi:10.2147/VMRR.S41005

  5. Śmiech, Anna et al. Occurrence and Distribution of Canine Cutaneous Mast Cell Tumour Characteristics Among Predisposed BreedsJournal of veterinary research vol. 63,1 141-148. 22 Mar. 2019, doi:10.2478/jvetres-2019-0002

  6. Fonseca-Alves, Carlos Eduardo et al. Current Status of Canine Melanoma Diagnosis and Therapy: Report From a Colloquium on Canine Melanoma Organized by ABROVET (Brazilian Association of Veterinary Oncology)Frontiers in veterinary science vol. 8 707025. 16 Aug. 2021, doi:10.3389/fvets.2021.707025

  7. Nishiya, Adriana Tomoko et al. Comparative Aspects of Canine MelanomaVeterinary sciences vol. 3,1 7. 19 Feb. 2016, doi:10.3390/vetsci3010007

  8. Tavasoly, Abbas et al. Classification and grading of canine malignant mammary tumorsVeterinary research forum : an international quarterly journal vol. 4,1 (2013): 25-30.

  9. Transitional cell carcinoma in dogs. University of Pennsylvania,School of Veterinary Medicine.