Cancer in Dogs

We love our pets, but they’re just as susceptible to heart-wrenching illnesses as we are. Cancer is no exception. It’s difficult to think about, yet pets also confront this dreaded disease. Responsible pet owners should be aware of the facts: Dogs can and do get cancer, and it is often treatable. Some breeds are more likely to be diagnosed with cancer than others.

Overrepresented and Underrepresented Breeds

Some breeds of pedigree dogs appear to be genetically predisposed to certain cancers, making it significantly more likely that they will be diagnosed with the disease than other purebred or mixed-breed dogs. In a recent study in Great Britain, researchers determined that cancer accounted for the deaths of 27% of all purebred dogs. An earlier study concluded that up to 45% of dogs over the age of 10 died from cancer in the United Kingdom.

As in humans, breast cancer (cancer of the mammary glands) is among the most common type of cancer in female dogs. The good news is that dogs who have been spayed at an early age enjoy a significantly reduced risk of this particular form of cancer. In contrast to human males, dogs do not develop prostate cancer with anything approaching the frequency that humans do. Oddly, prostate cancer, when it does occur, is slightly more likely to occur in male dogs that have been neutered.

Swedish researchers reported in 1997 that five breeds are among the most susceptible to fatal tumors. These breeds are the Bernese mountain dog, Irish wolfhound, flat-coated retriever, boxer, and Saint Bernard. Furthermore, Danish scientists concluded that Bernese mountain dogs, flat-coated retrievers, Golden retrievers, and rottweilers are the top five breeds in terms of cancer risk, with over 20% of deaths due to cancer in that country.

Other breeds deemed to be overrepresented in the cancer mortality tables are Afghan hounds, standard poodles, Weimaraners, Irish red and white setters, Staffordshire bull terriers, Cairn terriers, and old English sheepdogs. Some are particularly susceptible to specific forms of cancer. The Belgian shepherd, for example, is at increased risk for stomach cancer (gastric carcinoma), while the Scottish deerhound has a hereditary tendency to develop bone tumors (osteosarcoma).

Conversely, some breeds are especially unlikely to develop cancer. Among the most cancer-free breeds, statistically speaking, are border collies, cocker spaniels, Jack Russell terriers, dachshunds, and beagles. Mixed breed dogs tend to have lower rates of cancer, as well.

What Are the Warning Signs of Canine Cancer?

Just as in humans, early detection is important. See your veterinarian immediately if you have concerns. Here are some changes to look for:

1)    Foul odors coming from the mouth, anus or nose. This could be normal, or it could signal a tumor.

2)    Lumps under the skin. These could indicate a form of soft-tissue tumor. Act quickly, as tumors can grow rapidly.

3)    Inexplicable weight loss. This is a classic warning sign of possible disease.

4)    Loss of appetite. Like weight loss, this is a classic sign that something is not right.

5)    Lethargy, listlessness. There’s bored and lazy, and then there’s lethargic. The latter is not normal.

6)    Breathing abnormalities. Wheezing, coughing or struggling for breath could all signal lung cancer.

7)    Behavioral changes. You know your pet best. Has anything changed?

8)    Open sores. Wounds that don’t seem to heal are often a red flag.

9)    Vomiting and diarrhea. These can be common in dogs, but should not persist.