How to Tell If a Dog Has Tumors, Cysts or Cancer

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How to Tell If a Dog Has Tumors, Cysts or Cancer
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Cancer is a word with which we are all familiar given its prevalence. It is a disease that not only affects people, but our beloved family pets as well. At the time of this publication, up to 50 percent of dogs age 10 years or older will be diagnosed with cancer. Therefore, it is important for dog owners to recognize signs that could indicate the presence of cancer.


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If you observe concerning symptoms, your veterinarian can perform an evaluation and other diagnostic tests to determine the cause of the symptoms. Not all dogs bearing these symptoms will be diagnosed with a malignant cancer, but it is important to differentiate between benign and malignant conditions so they can be addressed appropriately.


Learn the Signs of Cancer

The Veterinary Cancer Society lists the following as the most common signs of cancer:

  • Abnormal swelling that persists or continues to grow
  • Sores that do not heal
  • Weight loss
  • Loss of appetite
  • Bleeding or discharge from any body opening
  • Offensive odor
  • Difficulty eating or swallowing
  • Hesitation to exercise or loss of stamina
  • Persistent lameness or stiffness
  • Difficulty in breathing, urinating or defecating


Although these are all symptoms that could point toward a diagnosis of cancer, there are other noncancerous diseases that will cause these signs as well. The tests that your veterinarian recommends will differentiate between a diagnosis of cancer or a different diagnosis. Take notice of the abnormalities so you can give your veterinarian an accurate picture of what has been going on and the duration of signs. For example, if your dog has a mass, note how long it has been present and whether it has grown in size since you noticed it. However, if you notice any of the above symptoms, don't automatically assume that your dog has cancer.


Establish Your Dog's 'Normal'

One of the most important ways to identify an abnormality on your dog is to become familiar with what is normal for his body. Veterinarians recommend performing a full body examination weekly to every other week that will allow you to identify any lumps, skin abnormalities or changes in muscle mass or weight that could indicate illness. You may incorporate this with a brushing or grooming session. Make it fun for you and your canine friend. New masses may indicate an infection or abscess, a benign growth such as a fatty lipoma or cyst or a malignant tumor such as a mast cell tumor. Some masses may represent enlarged lymph nodes.


Take note of your dog's urination and stool habits. Take notice if your dog loses interest in food and/or water for more than 48 hours.

Visit Your Veterinarian

Your veterinarian will recommend certain diagnostic tests or procedures based on what signs your dog demonstrates. Often the first procedures recommended include bloodwork to evaluate organ function and cell counts and X-rays or ultrasound to look for abnormal organ size, bone lesions or tumors within organs. To evaluate a lump or enlarged lymph node, your veterinarian may recommend a needle aspirate, which suctions cells out with a syringe or a tissue biopsy that removes a small piece of tissue. In cases of internal disease or to evaluate areas of the body that cannot easily be seen with other tests, such as the brain or nasal cavity, a CT scan or MRI may be recommended. The results of these tests will allow your veterinarian to make a diagnosis and suggest additional steps such as surgery, as well as tell you more information about your dog's prognosis.


Select a time once a week to perform a brief examination of your dog so changes can be noted quickly and addressed.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.