Cancer in Our Pets

Posted on Jul 24th, 2019, 10:29 AM America/Los_Angeles

By Tiffany L. Mitchener, DVM

It has to be among the most difficult moments for any pet owner:  The instant you discover your beloved pet has cancer. That dreaded word cancer can trigger a range of emotions.  Nearly every person in our community has been touched by cancer, whether through the loss of a pet or a friend or a family member.  According to the American Veterinary Medical Foundation, half of all dogs and cats over ten years old will get cancer. Half — that is a staggering amount!  This equals to roughly six million dogs and nearly the same number of cats diagnosed annually. In comparison, 1.7 million new cases of cancer will be diagnosed in humans this year.  


What is cancer?

Cancer is a broad term referring to the disease of unrestrained and abnormal growth of cells in the body.  It can arise from any type of body cell. In our dogs and cats, the most common types of cancer include cancers of the skin, bone, mammary gland, head and neck, testicles, abdomen, and lymphoma.  


How do I know if my pet has cancer?

It is not always easy to know if a pet has cancer.  Our pets are excellent at hiding their symptoms, and often owners will not know that anything is wrong.  Maintaining annual exams with a trusted veterinarian can be an important part of the cancer diagnosis. Early detection is key; often, the earlier a cancer is diagnosed, the more options there are for treatment.  A thorough history and a full physical exam are essential tools. Further testing may be recommended, often including x-rays, lab work, ultrasound exams, fine needle aspirates and/or biopsies. Rarely, advanced imaging may be recommended (CT or MRI scans).  


When should I bring my pet to the veterinarian?

Pets should be examined by a veterinarian if an owner has any health concerns, but especially if any of the following warning signs occur:

  • New lumps or bumps in the skin, especially if they are growing rapidly, changing appearance or bothering the animal
  • Sores on the skin that do not heal quickly
  • Significant weight changes, either weight loss or rapid weight gain
  • Loss of appetite
  • Persistent cough
  • Bad breath
  • Any difficulty breathing
  • Any difficulty eating or swallowing
  • Difficulties with urination or defecation
  • Any bleeding or discharge from the eyes, nose, mouth, or anus


My pet has cancer.  What do I do now?

A cancer diagnosis can be devastating and overwhelming for a pet owner.  A referral to a veterinary oncologist for a consultation can be very helpful.  A veterinary oncologist is a veterinarian with years of additional training in the diagnosis and treatment of animal cancers.  In a consultation, a veterinary oncologist can give an owner options for therapy, as well as information regarding prognosis, long term quality of life, and cost.  Together, the veterinary oncologist and owner can determine what is the best path forward for the pet.  


What is comparative oncology?

Did you know fighting cancer in pets can help us fight human cancer?  Comparative oncology is a relatively new medical discipline that integrates naturally occurring animal cancers into more general studies of human cancer biology.  Our pets live in our world. They share our homes, they share our adventures, they often eat the same food and drink the same water. Veterinarians have seen parallels between animal and human health for years, noting that dogs, especially, develop a lot of the same cancers as humans.  Now the human medical establishment is recognizing the importance of the canine model. The National Institute of Health has established comparative oncology trials which link networks of twenty-two medical academic research institutions with veterinary oncologists. Our canine companions help with clinical trials to test new cancer therapies that may benefit both veterinary and human medicine.  Dogs are truly the best model as they share intimately in their owner’s lives, they have shorter life spans allowing for efficient results, and there is a large dog population in our country. It is important to note that these clinical trials involve family pets not lab animals. These cancers are naturally occurring not lab induced. New and promising ways of battling cancer, such as immunotherapy or vaccination, are being researched today through our canine companions with the help of families seeking the best veterinary care for their dogs. 


Cancer is a dreaded diagnosis for everyone, both human and animal.  Far too many of our companion animals receive this diagnosis every year.  Early detection is important, and veterinary exams are essential for maintaining a pet’s health.  Seeking the advice of a veterinary oncologist after a cancer diagnosis may be a helpful step in a family’s path for the care of their pet.  It is even possible that a companion animal’s final act of love may be helping to further cancer research in the human and animal world.

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