Our best friends are a lot like us in one way we wish they weren't -- they get cancer at about the same rate we do. According to the National Canine Cancer Foundation, half of all dogs over age 10 will die of some form of malignance. That glum cloud has a silver lining: Cancer in dogs has been extensively studied for what it can reveal about human cancers. Largely because of this, veterinary oncology is now so advanced that, if caught early, canine cancer can be treated with every expectation of a positive outcome.
Some canine cancers are triggered by overexposure to environmental hazards, says veterinarian and oncologist Barbara E. Kitchell of the University of Illinois Veterinary Medicine Teaching Hospital at Urbana. Compared with people, dogs have a higher incidence of nasal cancer, which Kitchell attributes to chemical carcinogens such as herbicides and pesticides that become concentrated in dogs' noses after being sniffed up from the ground. Overexposure to sunlight is a risk factor for skin cancer in dogs, especially short-haired, fair-skinned breeds. The characteristic coloring of one particular breed, the Dalmatian, illustrates the protection afforded by dark pigmentation. "In Dalmatians," says Kitchell, "the cancer will circle around a black spot and won't enter the black skin."
When dogs are bred primarily for attributes considered desirable by humans, gene pool diversity is restricted, making predisposition to specific kinds of cancer more likely. According to a 2013 study published in "ISRN Veterinary Science," osteosarcoma, or bone cancer, "almost exclusively affects the large and giant breeds" such as Rottweilers, Great Danes, Irish wolfhounds, greyhounds and Saint Bernards. Some breeds, including golden retrievers and boxers, have the bad luck of being susceptible to multiple varieties of malignancy. Beagles, Scottish terriers and Airedale terriers are vulnerable to tumors of the lower urinary tract. But the numbers don't tell the whole story, especially regarding mast cell tumors originating on the skin. When boxers, bulldog breeds and pugs get these, they're less likely to be serious than in Labrador retrievers, for whom the tumors tend to be more aggressive.
Signs and symptoms vary depending upon the type and location of the malignancy. Excessive drooling, bleeding from the mouth and trouble eating or swallowing may be signs of oral cancer, according to the National Canine Cancer Foundation, or NCCF. If a dog is having difficulty breathing, lung cancer could be the reason. Weight loss accompanied by vomiting or diarrhea could be symptomatic of cancers affecting the digestive system. If dogs start limping for no apparent reason, bone cancer might be the culprit. Any unusual lumps, growths or sores on your dog's body should be investigated by your vet. But be vigilant, says Dr. Kitchell of the University of Illinois, because some dogs hide their symptoms, determined to please their owners by continuing to do things they really aren't well enough to do.
When detected early enough, many canine malignancies can be successfully treated using the same methods used on human cancer patients -- surgery, radiation and chemotherapy. Your vet, possibly in consultation with a veterinary oncologist, will be able to tell you whether the cancer remains localized or has spread, and offer a prognosis. From there, you may face some difficult decisions, financially as well as emotionally.
Like human cancer patients, every dog is unique, so many factors influence treatment costs. You can expect to spend about $200 for an initial evaluation, including diagnosis and discussions about treatment options. Surgery to remove a single tumor will start at about $1,500 but will run more if the tumor is located in a body cavity or hard-to-reach spot, says the NCCF. The dog's size will influence chemotherapy costs, but around $2,000 is average. If radiation is recommended, that will cost you around $5,000. On top of this, plan to spend an additional several hundred dollars on pain medications and antibiotics. Prices can vary widely between vets and treatment plans, so consult with more than one before going ahead.
- University of Illinois at Urbana-Champaign College of Veterinary Medicine: Cancer Risks in Cats and Dogs
- Science Daily: Variety of Genetic Risk Behind Bone Cancer in Dogs
- Wall Street Journal: When Cancer Comes With a Pedigree
- National Canine Cancer Foundation: Facts on Cancer
- ASPCA: Pet Care: Cancer
- ISRN Veterinary Science: Breed-Predispositions to Cancer in Pedigree Dogs
- New York Times: New Treatments to Save a Pet, but Questions About the Costs
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