Cancer is the No. 1 disease-related killer of dogs and cats, and one in three dogs will develop it, according to the National Canine Cancer Foundation.

It occurs in both purebreds and mixed breeds, but some cats and dogs are more susceptible to cancer than others. Both older cats and dogs are more likely to develop the disease than younger ones, and breeds like boxers, German shepherds, Great Danes and Boston terriers are more prone to certain types of cancer.

There's less breed-specific data on cats, but generally, cats with white heads and ears are more vulnerable to skin cancer.

While cancer can be treated through a variety of means, just like humans, an animal's best chance of survival is early detection.

Take a look at these 10 warning signs of cancer, but keep in mind that if your pet exhibits any of these symptoms, it doesn't necessarily mean cancer is the cause. If your cat or dog has one or more of these, see a veterinarian immediately.

1. Bumps and lumps

A veterinarian will typically do a biopsy on any unusual growths to determine if the cells are cancerous.

2. Offensive odors

Abnormal odors coming from an animal's mouth, ears or other body part can be caused by certain cancers.

3. Lameness, stiffness or evidence of pain

These could be symptoms of arthritis, especially in older pets, but they can also be signs of cancer.

4. Sores that don’t heal

Wounds or sores that continue to bleed or won't heal could be indicative of infection, cancer or another disease.

5. Coughing, wheezing or difficulty breathing

Abnormal breathing can be caused by cancer, as well as lung or heart disease.

6. Bleeding or discharge

Vomiting, diarrhea, pus, blood or any other abnormal substance discharged from your pet’s body should be checked out immediately. If your cat or dog’s abdomen swells, it could be a sign that fluid is accumulating in the body.

7. Changes in bathroom habits

Difficulty urinating or defecating, frequent bathroom use, or the appearance of blood in urine or stool are all potential signs of cancer.

cat ignoring food8. Lethargy

If your cat or dog starts sleeping more often, acts less playful or hesitates to exercise, let your veterinarian know.

9. Loss of appetite

Tumors can cause difficult chewing and swallowing, so any sudden change in appetite can be a sign of cancer.

10. Weight loss

If you notice weight loss in addition to any of these other signs, be sure to inform your veterinarian.

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Cat photo: /Shutterstock

Laura Moss writes about a variety of topics with a focus on animals, science, language and culture. But she mostly writes about cats.

How to spot cancer in your dog or cat
If your dog or cat shows any of these 10 symptoms, see your veterinarian.