Common Signs of Cancer in Dogs

Watching your dog grow old and experience health problems is hard— it leaves you worrying and wondering what you can do to help. One of the most common health problems in dogs is cancer. One in four dogs will develop it at some time in their life, whereas half of dogs over 10 years old will develop it. Early detection is key to helping a veterinarian treat it effectively.

How can you detect the symptoms to address the disease early and help your animal friend? Watch out for the following signs.

Abnormal Swellings

To be clear, not all abnormal swellings are cancerous. However, we do recommend testing all new lumps and bumps to make sure they are not cancerous. Masses can appear anywhere, so check for them as you are petting or grooming your dog. Training your dog early to tolerate brushing and petting is important so that they are not squeamish when you do it from time to time.

Weight Loss

Dog cancer, like cancer in humans, often causes rapid weight loss. When you cannot relate the symptoms to a known medical issue, it is a sign that something may be wrong. If you notice your pet is losing weight, we recommend bringing them to True Animal Vet for an exam and diagnostics.

Abnormal Odors

Tumors can cause bad smells, especially when coming from the mouth or ears. Abnormal odors can also be a sign of a dental problem or an ear infection. Again, it is best to take your dog to True Animal Vet for a thorough checkup.

Sores and Wounds That Do Not Heal

Persistent sores and wounds can indicate that your dog has compromised immunity. It shows that their body is not functioning and fighting infections optimally. Cancer can also look like sores or wounds that do not heal. Once you notice these, seek medical assistance—the earlier, the better. Surgical removal is often indicated.


Seizures can happen for many reasons, but they are especially concerning in older dogs if they have not had seizures before. A seizure is classified by a loss of consciousness, collapse, and convulsions for an average of 30-60 seconds. It often takes a few minutes for them to recover after the seizure stops. They are the hallmark feature of a brain tumor in older pets, so emergent veterinary care is recommended. Other signs of a brain tumor are changes in personality, lethargy, sudden blindness, squinting of the eyes, and pressing of the head into walls.


Cancer can cause various levels of discomfort and pain. Bone cancer, in particular, can be very painful. When you notice that your dog is reluctant to engage in physical activity, limping, or displaying lameness, seek medical attention. While most pets will just need treatment for arthritis, it is always important to rule out cancer as the cause of discomfort.


Coughing or Trouble Breathing

There are many reasons for a dog to cough, but it is especially concerning in older patients. They are more likely to develop serious conditions such as lung cancer, pneumonia, and heart disease. If your pet is coughing, we strongly recommend an examination and radiographs (x-rays) of the chest to better assess why they are coughing.

For more information on common cancer signs in dogs, contact True Animal Vet at our office in The Woodlands, Texas. Call (281) 867-5968 to schedule an appointment today.

Dr. Kathryn Salcetti
Director of Urgent Care
True Animal Vet

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