Warning Signs of Cancer in Dogs

Lethargy or Depression

When dogs are lethargic, depressed or just "not right," it usually means something is wrong with their health. If it resolves on its own, then this is something to make a mental note of. However, if changes in activity level, mood and/or behavior persist for a few days or are combined with other symptoms, you should contact the vet.

Weight Loss

There are a variety of health problems that can cause a dog to lose weight. Sometimes dogs with normal appetites even lose weight. Talk to your vet if your dog seems to be losing weight (without trying). It might be cancer or another disease.

Appetite Changes

A decrease in appetite often goes along with weight loss. However, some dogs might still eat fairly well and maintain weight but seem less enthusiastic about food or simply picky. Trouble eating or swallowing is also something to act upon. Contact your vet if your dog's eating habits change, especially if it occurs in conjunction with other signs.

Vomiting or Diarrhea

Vomiting and diarrhea may occur for a number of reasons. While not always associated with cancer, they are things to address regardless of cause. If vomiting or diarrhea persist and treatments for common causes don't work, your vet may recommend additional diagnostic tests to look for cancer.

Similarly, difficulty urinating and/or constipation should be noted and reported to the vet.

Lumps and Bumps

Lumps, bumps, growths, masses, or tumors can appear just about anywhere on or in the body. Many lumps and bumps are benign growths. Some may come with age or genetics. Your vet should be the one to decide which growths are concerning.

See your vet if your dog develops new lumps/bumps. In addition, visit the vet if existing lumps/bumps change in shape or size, rupture, develop a discharge or if they begin bothering your dog. Your vet will run tests to pinpoint the type of lump and determine if treatment is necessary.

Persistent Lameness or Pain

A mild limp can be related to an injury, but, if rest and medications do not make the problem go away, be sure to let your vet perform X-rays and other tests as indicated. Sudden, severe pain accompanied by a limp is always a cause for concern. Bone cancer, can cause either persistent or acute lameness, but diagnostic testing is needed to differentiate it from other chronic conditions, like arthritis.

Pain in the abdomen and other areas of the body can also be caused by a number of things, and cancer is one of them.

Distended Abdomen

If your dog's abdomen looks enlarged or bloated, you should go to the vet as soon as possible. There are a few conditions that can cause the abdomen to become distended. A tumor in the abdomen may lead to fluid buildup, enlarging the abdomen even if the tumor itself is still relatively small. Anther potential cause is a deadly condition called GDV or "bloat."

Abnormal Discharge or Bleeding

Blood or drainage from the skin, nose, mouth, eyes, ears, anus, or genitals are all reasons to see the vet right away. Potential causes of this can range from minor infection to major illness. Even if the reason is not cancer, it's an issue that needs attention.

Strong Odor From Mouth

Your dog's breath might be bad due to dental disease, and this alone is reason enough to see the vet. However, strong odors, especially when they come on suddenly and/or no dental disease is present, can also be seen with tumors within the mouth. Additional signs to look for include swelling in the face and apparent shifting of the teeth.

Abnormal Gum Color

A healthy dog's mucous membranes (gums, cheeks, insides of eyelids) and tongue should be nice and pink (black color from pigment is also normal). Pale, white, gray, or blue mucous membranes indicate a big problem.

Additionally, a yellow tinge to the mucous membranes, whites of the eyes, and or skin is indicative of jaundice that is typically seen with liver disease or disorders affecting red blood cells.