Cancer Awareness

Cancer in Pets

Cancer affects all of us, whether through a family member, a close friend, a teacher or a beloved pet. There are approximately 165 million dogs and cats at risk for cancer in the United States. This translates into nearly 4 million dogs and 4 million cats developing cancer each year. It is estimated that nearly 50%of all dogs and 32% of all cats over the age of 10 will develop cancer, making it the leading cause of death in our pets.

The term cancer describes a large number of diseases with the common feature of uncontrolled cell growth. The development of cancer depends on multiple factors. Environmental and genetic contributions often result in an accumulation of errors in the cell leading to uncontrolled growth. Breed, gender, and environmental factors all play a role in the development of cancer.

Warning Signs of Cancer in Pets

Early cancer detection is associated with best outcomes and in many cases a cure. It is important for owners to accurately recognize possible “warning signs” of cancer in their pets. If noted, it is important to contact the primary care veterinarian for a thorough examination.

10. Lumps and Bumps

Not all lumps and bumps on or under the skin are cancerous. It is important to bring this to the attention of your primary care veterinarian to further investigate. A needle aspirate or biopsy are routine procedures to help determine benign from malignant. Needle aspirates are painless, typically do not require sedation or anesthesia, and often reveal the underlying cause of the skin lump. In some cases, a needle aspirate cannot be performed and a biopsy under light sedation or general anesthesia may be recommended.

  1. Abnormal Odors

Offensive odors from your pet’s mouth, ears, or any other part of the body, should be checked out. Oftentimes cancers of these regions can cause foul odors as a result of secondary infections. Tumors, unlike normal tissue, are more susceptible to infection especially when located in certain areas of the body such as the mouth, the ears and around the anus. A thorough physical examination can often determine the location and cause of the odor.

  1. Abnormal Discharges

Abnormal fluid discharge from any part of your pet’s body should be checked out by your veterinarian. Some cancers may produce fluid while others may put pressure on the normal drainage system in the body leading to a back up fluids. A thorough physical examination can often determine the location and cause of the discharge.

  1. Non-Healing Wounds

If your pet has wounds or sores that are not healing, it could be a sign of infection, skin disease, or cancer. Unlike normal tissue which has the ability to heal itself, tumors do not contain this property and to the pet owner, this may appearas a non-healing wound. An examination and tissue sample can often determine the underlying cause.

  1. Weight Loss

Cancer can cause weight loss in a pet. If sudden weight loss is noted in your pet this should be evaluated by a veterinarian. Cancer may prevent normal intake of food or cancer can compete with the body for important nutrients, leading to weight loss. A thorough physical examination, routine laboratory diagnostics and in some cases imaging (radiographs or ultrasound) may be required to determine the underlying cause.

  1. Change in Appetite

Pets generally do not stop eating without an underlying reason. A recent lack of appetite could be a result of an underlying cancer and should be evaluated. Cancer may affect normal intake of food through either the development of nausea or the physical presence of the tumor (oral cavity of gastrointestinal tract).

  1. Coughing or Difficulty Breathing

Coughing or changes in breathing can be a result of heart disease, lung disease, or cancer. If this is noted your pet should be evaluated by your veterinarian. Cancers located within the respiratory system can affect the normal respiration process, resulting in changes in breathing and/or cough. A thorough physical examination with special emphasis on the respiratory system through auscultation is warranted. In some cases chest x-rays may be required to visualize the chest cavity in more detail.

  1. Lethargy or Depression

If you notice your pet is less active, sleeping more, or less interactive, these can be signs of cancer and should be evaluated further. Cancer, depending upon the type and where it is located, may result in minor discomfort or affect normal exercise which may manifest as lethargy and/or depression.

  1. Changes in Bathroom Habits

Changes in your pet’s urinary or bowel habits may be potential signs of cancer. Straining to urinate or defecate, blood in the stool or urine, more or less frequent eliminations, are some symptoms of cancers located in the urinary or gastrointestinal system. An examination, routine diagnostics and often more advanced imaging such as an ultrasound is often required to properly assess the cause of these symptoms.

  1. Evidence of Pain

Limping or other evidence of pain is generally more likely associated with arthritis or muscular injury, but it can also be a sign of cancer (especially cancer of the bone) and should be evaluated by your veterinarian.  A routine physical examination and gait evaluation can often localize the region of the body from which the lameness is occurring. Radiographs of the affected area can often help elucidate the underlying case.


Submitted by:

Kate Vickery, VMD, MS, Diplomate ACVIM, CVA

Craig A Clifford DVM, MS, DACVIM (Oncology)

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