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Early Warning Signs of Cancer in Dogs


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Cancer is typically seen in older dogs, however, some cancers can be found in younger dogs as well. There are four types of cancers common to dogs. These include bone cancer, mammary gland cancer, lymphoma, and skin cancer. If you suspect your dog might be ill, you may want to consider educating yourself on early warning signs of cancer and watch your dog carefully, along with your vet providing proper preventive veterinary care. Catching some cancers early by knowing the signs is the best way to help your dog fight the disease.


Lumps or bumps under the skin are sometimes tumors. Petting your dog is the easiest way to discover if they have swelling or weird lumps forming that could potentially be cancerous. You can turn playtime into a cancer check by simply giving your dog affection. You may also notice swelling in areas of lymph nodes or around your dog’s neck and face. These are all signs to visit your veterinarian right away, even if only for peace of mind.

Sores Which Don’t Heal

Another sign of cancer are sores that don't heal easily or at all. Wounds on the surface of the skin that scab over, appear to go away, and continue to come back is a sign that something is not quite right with your dog’s overall health and immune system. Skin cancer is often discovered by observing the lack of healing on the skin. Sores that do not heal quickly or at all could also mean your dog’s immunities are too weak to heal that part of the body. This usually means their immune fight is elsewhere within the body.


Sometimes dogs smell like dogs. But if an unusual, unpleasant odor is emanating from your dog it could potentially be a sign of a cancerous tumor. Tumors found within your dog’s mouth, nose, or other orifices can create an offensive odor that is quite unlike the smell of a dog in need of grooming.

Loss of Appetite and Weight Loss

If your dog has lost interest in their food and is losing weight, they may be ill. Cancer is only one disease your veterinarian will want to look at and consider if your dog's appetite or weight changes. Loss of interest in activity and foods is a typical first warning of any health trouble from just not feeling well to something more serious like cancer.

Unusual Bleeding or Discharge

If your dog bleeds without explanation or visible injury, or if your dog is experiencing blood in their urine or stool, have them examined by your veterinarian. Discharging vomit and diarrhea could also be signs of trouble within the body.

Difficulty Swallowing

Your dog could potentially have throat cancer or cancer in their mouth if they are showing signs of pain when they try to swallow. Your dog will also probably show an interest in food without the desire to eat.


If your dog's energy is suddenly lower than normal, this is a sign they are not feeling well. Lethargy is one of the first symptoms of illness.


Your dog may potentially be experiencing pain for various reasons. Lameness could result from cancer within soft tissue nerves or bones. Have your dog checked out by your veterinarian if they are favoring a limb over others and walking with a lame gait.

Prevention and Early Detection

There several kinds of cancer your dog can develop. Preventive care through your veterinarian with regular visits and watching for early signs are your best chance of catching something serious early. Providing a high-quality diet with added supplements, or fresh fruits and vegetables for antioxidants, and keeping their calorie counts down to keep your dog at a healthy weight are preventive measures easily done from an early age. Cancer cells thrive in glucose, so dogs with diets high in sugar may be more susceptible to developing cancer than dogs who have been eating a healthy, lean protein diet with a reasonable fat content.

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