Causes of Cancer in Dogs to Be Aware Of

Updated August 18, 2021
Walking Golden Retriever outdoor

If your pet has received a cancer diagnosis or you're hoping to minimize your healthy pup's chances of developing the big C, you may wonder what causes cancer in dogs. Unfortunately, canine cancer is incredibly unpredictable, but numerous factors can contribute to these malignant diseases. By understanding the contributing components, you can protect your pet by remaining aware of their risk or avoiding harmful exposure.

What Causes Cancer in Dogs?

Although many pet owners associate cancer with old age in dogs, that's not always the case. Doctor Adriana Alire, an emergency and general practice veterinarian with a special interest in oncology, says, "We just never know when cancer will arise in a patient. I have seen patients as young as 2 years old diagnosed with neoplasia such as brain tumors or nasal carcinoma." We do know that cancer is uncontrollable abnormal cell growth that can be a result of various factors.

Genetic Factors

Your pet's breed or size might be to blame for certain cancers. Alire agrees that genetic predisposition, such as breed or hereditary makeup, can be involved in the development of specific diseases. That's not to say your dog will inevitably develop one of these cancers just because they are a specific breed, but they are at higher risk. It's important to keep a watchful eye for the early signs of these cancers.
Some common dog breeds and their respective cancer predispositions include the following.

  • Any large breed dogs - osteosarcoma
  • Any light-colored dogs - cutaneous hemangiosarcoma and squamous cell carcinoma
  • Beagles - transitional cell carcinoma
  • Boxers - lymphoma and mast cell tumors
  • Cocker Spaniels - anal gland adenocarcinoma
  • German Shepherd Dogs - hemangiosarcoma and anal gland adenocarcinoma
  • Golden Retrievers - lymphoma, mast cell tumors, fibrosarcoma, and oral melanoma
  • Labrador Retrievers - lymphoma and mast cell tumors
  • Rottweilers - lymphoma, histiocytic sarcomas, and osteosarcoma
  • Staffordshire Bull Terriers - mast cell tumors
  • Standard Poodles - squamous cell carcinoma of the digit
  • West Highland White Terrier - transitional cell carcinoma

Hormonal Factors

Hormones can play a role in a dog's risk of cancer. Reproductive hormone production by the ovaries of an intact female dog can put them at high risk for developing mammary cancers. Statistically, a female dog spayed before their first heat cycle has less than a 1 percent chance of developing mammary masses, whereas a dog spayed after their first heat has an 8 percent risk, and one spayed after their second has 26 percent risk. With subsequent heat cycles, a dog's risk of mammary cancer increases. Fixing a female dog and removing their ovaries will halt hormone production and reduce the risk of these tumors developing.

Environmental Factors

Unfortunately, certain environmental hazards such as pesticides, air pollution, or smog can put your dog at risk of developing cancer. Although most of these carcinogens are out of our control, you can try to limit your pet's exposure to potentially harmful sprays or materials.

Exposure to ultraviolet (UV) radiation from the sun can lead to canine skin cancers such as cutaneous hemangiosarcoma, hemangioma, or squamous cell carcinoma. This is particularly prevalent in dogs with short hair, a sparse or light hair, or non-pigmented skin. To prevent this exposure, try to keep your dog out of the sun during peak UV hours, provide adequate shade outside, and apply protective UV barriers to your windows if they enjoy sunbathing indoors. Owners of dogs with white fur or pink skin should take extra precautions by applying a dog-safe sunscreen product or protective clothing.

Dog relaxing park

Lifestyle Factors

Second-hand smoke has been linked to respiratory issues in dogs as well as high rates of nasal and lung cancers. Third-hand smoke is also a danger to your pets. Smoke residue can attach to your clothing, skin, and other surfaces that your pet can ingest through licking or potentially inhalation. If you smoke tobacco, be sure to do it away from your dog, then wash your hands and arms, plus change your clothes before interacting with your pet.

Infectious Factors

One type of canine cancer is contagious and can be transmitted through direct contact with an infected dog. Transmissible venereal tumor (TVT) presents as tumors on the genitalia and is most prominent in intact mixed-breed dogs. It is spread through sexual contact or sniffing or licking the tumors; therefore, it's critical to keep affected dogs away from others to avoid spreading this malignant disease. This type of cancer typically doesn't metastasize to other organs of the body.

Treatment Options for Canine Cancer

The possible treatment options for your dog depend heavily on the type and location of their cancer. Ultimately, the goal is to eliminate any cancer cells from the body, which may require localized or systemic solutions. If complete eradication is not possible, slowing the cancer or treating the symptoms associated with it may be the next best plan of action.

Your veterinarian may refer you to a veterinary oncologist to develop a personalized plan to address your pet's case. Standard treatments may include one or a combination of the following options.

  • Surgical removal
  • Oral chemotherapy
  • Injectable chemotherapy
  • Radiation therapy

The Future of Cancer Detection in Dogs

Exhaustive research is currently being performed to determine what exactly causes cancer in dogs and to help identify early indicators. By analyzing the DNA of dogs -- both those that develop cancer and those that do not -- throughout their lifetime, researchers can potentially determine biomarkers that may predict cancer. One such study is the Golden Retriever Lifetime Study, whereby pet owners enroll their young Goldens and send routine blood samples for analysis.

Although there's no definitive way to say what could cause or has caused your dog's cancer, know that many of the contributing factors are out of your hands. Approaching the situation with compassion and making your dog as comfortable as possible with the time they have left is the best care you can provide.

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Causes of Cancer in Dogs to Be Aware Of