Common signs of cancer in pets

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 rate of cancer in cats. 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 on 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 diagnosis of cancer, 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 be seen by your veterinarian to try and determine a cause. The work up for this usually starts with bloodwork, 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 the dog 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 bloodwork 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  uncovers that the mass is of concern. As dogs get older they can develop new masses like lipomas (fatty mass), which are benign. Any new masses should be evaluated so your local veterinarian can help guide you as to what the best treatment options might be. In some cases monitoring may be the best treatment option, but only after you determine what it 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 be able to provide more treatment options and improve 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: bloodwork, 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. Any time you notice that your pet has had an unexplained drop in their weight they should be seen. Weight loss is sometimes one of the first indicators in the diagnosis of cancer.  The first steps are very similar to what has already been stated and usually includes bloodwork, 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 and rarely other bones in their 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 (ie bloodwork 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 the treatment options and prognosis with you. Fortunately, dogs and cats tolerate most cancer treatments very well. The goal with any cancer treatment is 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 as long as possible. We believe quantity of life is meaningless without quality.  It is important to realize that you know your pet best and criteria for determining one animal’s quality of life may not fit for another.  Being armed with the correct information allows you to be the best advocate for your pet.