What causes cancer in our pets?
Gerald S. Post, DVM, MEM, DACVIM (Oncology)
Veterinary Oncology & Hematology Center, LLC
Back to main cancer page.
This is one of the most common questions I get asked as a veterinary oncologist. Generally, we are not able to tell why an individual pet develops cancer. However, cancer is caused by a multitude of factors including genetics, diet, environment, etc. Anything that can cause cancer in humans can cause cancer in pets. Below, I will discuss some specific, known causes of cancer in our pets.
Is my pet's cancer genetic?
Pet owners ask me this question on a daily basis and the answer isÉYes. All cancer is genetic in origin as cancer results from errors in DNA Ð the instruction manual for how our cells work. Abnormalities in DNA that cause cells to divide rapidly and/or cause cells not to die, result in cancer. All cancers are due to genetic problems, but that does not mean they are heritableÑin fact, most cancers are not passed from parent to child (inherited). There are only very few reports of possible heritable cancers in veterinary medicine, including a family of Rottweilers diagnosed with lymphoma. Examples like this, however, are few and far between.
At the Veterinary Oncology and Hematology Center (www.oncovet.com), we are currently collaborating with the Broad Institute and VARI in collecting blood samples to look for genetic abnormalities in dogs which may be linked to cancer development.
Are certain breeds predisposed to cancer?
There are certain breeds which are more likely to develop cancer. Golden Retrievers are predisposed to cancer in general. Boxers are predisposed to T-cell lymphoma and mast cell tumors. Bladder cancer (transitional cell carcinoma) is more common in Scottish Terriers, West Highland White Terriers, Shelties and Beagles. Large and Giant breed dogs are more likely to develop bone cancer (osteosarcoma). Bernese Mountain dogs, Flat-Coated Retrievers and Rottweilers have a higher incidence of histiocytic sarcoma than other breeds.
Can smoking increase my pet's risk of cancer?
Yes. There was a study which found an increased risk of feline lymphoma in households where cats were exposed to environmental tobacco smoke. The hypothesis is that a cat's self-grooming leads to the ingestion of the carcinogens found in the tobacco smoke that gets deposited on the hair coat of these cats. It was also found that cats exposed to environmental tobacco smoke were more likely to develop oral squamous cell carcinoma.
Does sun exposure cause cancer in pets?
Potentially. In white or partially white cats with minimal skin pigmentation, sun exposure is associated with facial squamous cell carcinoma. There is some evidence that sun exposure may play a similar role in dogs with cutaneous squamous cell carcinoma and cutaneous hemangiosarcoma.
Is there any benefit to spaying (ovariohysterectomy) my dog or cat as it relates to breast cancer?
Yes. Dogs and cats that are spayed prior to their first heat cycle have a much lower risk of developing mammary tumors (breast cancer). Dogs spayed prior to their first heat cycle have only a 0.05% risk of developing malignant mammary tumors. Dogs spayed between their first and second heat cycle have a 8% risk of developing malignant mammary tumors and dogs spayed after their second heat cycle have a 26% risk for developing malignant mammary tumors. Cats spayed prior to 6 months of age have a 91% reduction in risk for mammary cancer as compared to unsprayed cats.
Are there any associations with vaccination and cancer development?
Likely. There have been epidemiologic studies in cats which support the association of inactivated vaccines (Feline Leukemia Virus and rabies) with future soft tissue sarcoma development at the injection sites. It is thought that the vaccine causes an inflammatory reaction which leads to uncontrolled cell growth in the area of the vaccine which can eventually lead to tumor formation. It can take anywhere from months to over ten years for a vaccine to result in a sarcoma. The prevalence of these vaccine associated sarcomas is anywhere from 1/1,000 cats to 1-3.6/10,000 cats. Obviously the overwhelming majority of cats are at a fairly low risk for tumor development after vaccination and proper vaccinations play a vital role in keeping the cat population healthy. There have been some proposed measures that can be taken to decrease the risk of vaccine induced sarcoma, but they are somewhat controversial. One of the more common recommendations is to use nonadjuvanted vaccines. Most importantly, the benefits and risks of vaccinations should be discussed with your local veterinarian.
THIS SITE PROVIDES INFORMATION, NOT MEDICAL ADVICE
Information on this web site is provided for informational purposes only and is not intended as a substitute for the advice provided by your veterinarian or any information contained on or in any product label or packaging. You should not use the information on this web site for diagnosing or treating a health problem or disease, or prescribing any medication or other treatment. You should always speak with your veterinarian before giving any medication or nutritional, herbal or homeopathic supplement to your dog, or adopting any treatment for a health problem. For any products or services purchased from this web site, you should read carefully all product packaging and instructions.
| 
