Cancer occurs when a normal cell mutates or changes into an abnormal cell, which then multiplies rapidly. This original source of cancer starts in one organ and then can spread (or metastasize) via blood and the lymphatic system, to other organs, especially the lungs. Animals are just as susceptible to cancer as humans. Research has shown that cancer is influenced by genetics, which means that the tendency to develop cancer can be hereditary. The tendency to get cancer can be influenced by various elements of the environment including secondary cigarette smoke, radiation, radon gas, poor diet and toxic chemicals. Furthermore, diseases that weaken the immune system like feline leukemia or feline aids leave cats more susceptible to developing cancer. Cancer can affect any organ system, including the skin. Skin cancer is common in white and pink-skinned dogs and cats. The lesions usually appear on the ears, nose, stomachs or around the eyes. Using waterproof SPF15 sun block on exposed areas of your pet’s skin can help reduce the risk of cancer in higher-risk animals. Breast cancer is one of the most prevalent forms of cancer in female pets just as it is prevalent in female humans. However, it is the easiest form of cancer to prevent in animals if you have your pet spayed before she has any litters since it usually occurs in older, un-spayed females. Spaying your dog or cat before they have their first heat cycle reduces the likelihood of acquiring the disease by 90 percent!


  • Spay or neuter your pet as soon as possible. This prevents ovarian, breast, prostate and testicular cancers from occurring.
  • Feed your pet a high quality pet food.
  • Use waterproof sun block on skin areas that are unprotected by hair and exposed to the sun.
  • Protect your pet from secondary tobacco smoke.
  • Check your home for radon gas.
  • Avoid feeding your pet artificial colorings, flavorings and preservatives.
  • Check your pet regularly for lumps and bumps or masses under the skin.
  • Watch for symptoms, especially in older pets, such as weight loss, behavior change, prolonged vomiting and diarrhea, increase or decrease in food or water.
  • Annual physical exams by your veterinarian are important and senior pets should be examined every 6 months.

Cancer treatment varies depending on the type of cancer and how advanced the cancer is at the time of diagnosis. Of course early diagnosis is always very important for successful treatment. Surgical removal of tumors is recommended; however, if the tumor is diffuse or has already spread then radiation and chemotherapy are used.

Board certified veterinarians are called oncologists and have extra training in the diagnosis and treatment of cancer. These vets specialize in treating patients with cancer and use the most recent methods of treatment available. Your veterinarian can refer you to an oncologist if need be.

Please note, articles in the Animal Resource Library are for reference only, and are not meant to diagnose or treat any medical or behavioral issues your pet may be experiencing.