Detecting Signs and Symptoms of Cancer in Your Pet

We all love our pets. They are our furry children, companions, and cuddle buddies. The thought of cancer strikes fear into the hearts of many pet owners, not only because the finality of the disease could mean saying goodbye, but because, above all else, we hate to see our loved ones suffer. However, cancer can present itself in a myriad of ways, and can sometimes be mistaken for signs of aging or a minor illness. Here are the top ten signs and symptoms that your pet may have cancer. You should consult your veterinarian if you notice any of the following signs and symptoms of cancer in your pet:


  1. Lumps and Bumps – Not all bumps are tumors, and not all tumors are malignant. However, it’s nearly impossible to tell what a growth could be unless it gets palpated or biopsied by a professional. Tumors are often referred to as neoplasms – neoplasia means ‘new growth.’ Bumps on your companion animal’s skin or lumps on their body can also be papilloma, cysts, or abscesses, but you should have your veterinarian look at the growth to check.
  2. Sudden Weight Loss – If your pet is not on a diet and begins to lose weight rapidly without a change in exercise or feeding, it may be a sign of cancer if coupled with other signs and symptoms. Typically drastic weight loss is about 10% of your pet’s weight in a short time period.
  3. Lethargy and Behavior Changes – You know your pet well, and you know what their typical energy level is. Reduced energy levels can indicate other issues, especially after a move or life change for your pet, or the death of a family member, but it has been noted that lethargy is very common in companion animals with cancer.
  4. Respiratory Issues – Coughing and difficulty breathing can mean that cancer has metastasized in your pet’s lungs, which is very serious. It’s also a symptom of heart and lung disease, or kennel cough. In the latter case you should keep your pet away from other animals and in any case see your veterinarian.
  5. Abnormal or Foul Odors – We know dogs get gas, but occasionally it can mean something other than the fact they got into the trash. Persistently stinky breath or rotten smells from either end could mean infection, not to mention mouth or intestinal cancer.
  6. Abnormal Discharges – If you notice unusual body fluids emanating from various body parts, have your pet checked by your veterinarian immediately.
  7. Lack of Appetite – Changes in eating habits can harm your pet’s health drastically, and are almost always a sign of something wrong. A decrease in appetite isn’t necessarily a sign of cancer, but it can mean that your pet has an oral tumor that makes it difficult to chew and swallow.
  8. Accidents in the House – Changes in the frequency of your pet’s bathroom habits, or accidents in the house are never a good sign. Blood in urine or stools is also an issue. Your veterinarian will want to take samples and know how your pet’s habits have changed, so if you can, take notes.
  9. Outward Signs of Pain – If your pet is limping, whining while moving, or having difficulty getting comfortable while lying down, he or she may have a type of bone cancer, which can become serious very quickly. Have your veterinarian examine your pet as soon as possible.
  10. Wounds that Won’t Heal – Injuries or sores that won’t heal are never a good sign. Lacerations or cuts that may need stitches and go untreated can also become infected and turn septic.


If your pet is showing some combination of two or more of these signs, visit your veterinarian. Many of these signs are associated with other, less severe health problems that can be easily treated and managed. If your pet is diagnosed with cancer, early treatment can give the best results. Talk to your veterinarian about treatment options and how to maintain the best quality of life for your companion animal.

  1. Thank you for the article. I will know exactly what to look for before I take my dog Newman to the vet. I have noticed that he has been losing weight very rapidly this past week. He is a grey lab, does breed have any impact on the dog’s susceptibility to cancer?