Symptoms of Cancer in Dogs & Cats

Common Signs of Cancer in Pets

Common Signs of Cancer in Pets: A Great Dane Looks Outside Through a Window

Treating cancer in pets is a large part of what we do here at AVIM&O. An estimated 4 million dogs and cats will develop cancer each year. As dogs get older, their risk of cancer increases. Almost half of dogs over the age of 10 will develop cancer, while there is less information regarding the cancer rate in cats. Still, we do know that cancer is the leading cause of death in 47% of dogs and 32% of cats.

A Morris Animal Foundation study found that 41% of animal owners feel that cancer is the biggest health concern for their pet. It is very difficult to detect cancer early in pets, and unfortunately in most cases, cancer cannot be detected with routine blood work.

However, according to the American Veterinary Medical Association, there are 10 things you can look for. These signs are not definitive for a cancer diagnosis, but they may be able to detect another medical condition early that might require additional veterinary attention and/or treatment. Early detection is key when dealing with cancer, so learn to spot the signs discussed here:

  • Abdominal swelling. This can be a slow or quick onset and it is important to see your veterinarian to try and determine a cause. The work up for this usually starts with blood work, a urine sample, and an abdominal ultrasound.
  • Bleeding from the mouth, nose, or other parts of the body. Melanoma is the most common oral tumor in dogs, and squamous cell carcinoma is the most common oral tumor in cats. Seeing your local veterinarian twice a year for routine examinations can help to identify these tumors sooner. Early detection of these tumors has shown to result in an improved outcome. So if you notice your pet has blood-tinged saliva, is eating slower, has colored discharge from the nose or bleeding from any other areas of the body, the best thing is to have them evaluated by your veterinarian. In most cases some additional testing will be recommended to try and determine a cause and diagnosis.
  • Difficulty breathing. Any time there is a concern that your pet is having difficulty breathing, they should be evaluated immediately either at your local veterinarian or the closest emergency clinic. Evaluation with blood work and radiographs of the chest will likely be recommended as a starting point to try and determine a cause.
  • Difficulty eating or swallowing. This could be a sign of dental disease or something more serious and warrants a visit to your local veterinarian for further evaluation.
  • Lumps, bumps or discolored skin. Any new mass found on your pet should be aspirated by your local veterinarian to determine whether additional steps should be pursued. After the aspirate, a next step may include taking a small biopsy sample (called an incisional biopsy) to gain a better understanding of the mass vs. complete excision if the aspiration reveals that the mass is a concern. As dogs get older they can develop new masses like lipomas (fatty masses), which are benign. Any new masses should be evaluated so your local veterinarian can help guide you towards the best treatment options available. In some cases, monitoring may be the best treatment option, but only after you determine what the condition is.
  • Non-healing wounds. Most cuts and scrapes will heal on their own. Unfortunately, if your pet has a sore that is not improving after a few days to a week, they should be seen by your local veterinarian. Cancer is able to do a lot of things, but it cannot heal and usually continues to grow. Getting to a malignant tumor sooner allows the doctor to provide more treatment options and improve the outcome for most pets.
  • Persistent diarrhea or vomiting. Dehydration can occur quickly, even if your pet is still drinking. If they have had more than 3-4 vomiting episodes in a day or more than 36 hours of diarrhea, then they should be seen by your local veterinarian. The sooner they are seen the lower the chances are that they will require hospitalization. Tests that will be recommended usually include: blood work, analysis of urine, X-rays, and possible ultrasound. There are many benign causes of vomiting and/or diarrhea, but cancer is always a concern and should be ruled out as a possible cause.
  • Sudden or chronic changes in weight. If you notice that your pet has had an unexplained drop in their weight, they should see their veterinarian immediately. Weight loss is sometimes one of the first indicators of a cancer diagnosis. The first steps are very similar to what has already been stated and usually include blood work, a urine sample, radiographs and/or an abdominal ultrasound.
  • Unexplained swelling, heat, pain or lameness. There are a lot of different causes for these signs in dogs and cats. Any persistent swelling, pain or lameness that does not improve with supportive care should be investigated further. In dogs, a bone tumor called osteosarcoma can cause a firm swelling in either their front or back legs, but rarely in other bones in the body. Most of these dogs will improve initially with pain medications and anti-inflammatories, but it never completely resolves and the swelling remains. If this is the case, then along with initial diagnostics (i.e. blood work and a urine sample), radiographs of the affected limb are recommended. If there are changes noted in the bone, the next steps usually include chest radiographs and either an aspirate and/or biopsy with culture of the concerning area in the bone to try and arrive at a diagnosis.
  • Visible mass/tumor. As stated above under lumps, bumps or discolored skin, any new mass should be evaluated with aspiration. Based on the aspirate results, further recommendations can be made.

If your pet is diagnosed with cancer, the next step is being referred to an oncologist where they will discuss your pet’s prognosis and treatment options with you. Fortunately, dogs and cats tolerate most cancer treatments very well. The goal with any cancer treatment is to ensure that your pet maintains a good quality of life before, during, and after treatment. However, in many instances a cure is not possible. In these cases, our goal is to achieve a good quality of life for your pet for as long as possible. We believe quantity of life is meaningless without quality. It is also important to realize that you know your pet best, and the criteria for determining one animal’s quality of life may not suit another. Being armed with the correct information allows you to be the best advocate for your pet.