Written by: Dr. Bob Rosenthal, Veterinary Oncologist
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Editor’s Note: This is an article from last April that we will probably repost every year because the information is so valuable. As most of you probably know, Orvis partners with the Morris Animal Foundation to raise money to support research into canine cancer, and it’s a cause that Orvis Dogs is passionate about.
Cancer is a word that has long held a strong emotional impact. The word itself is derived from the Greek word for crab. The Greeks made the association recognizing some shared characteristics of the disease and the animal, the firmness and tenacity seen in both. Today, we have a much more sophisticated, although still imperfect, appreciation of what cancer is, but many questions remain. In the future, I will address questions on OrvisNews.com about how cancer affects our pets, explain how specific cancers are diagnosed and treated, and look at the good work of the Morris Animal Foundation that the Orvis Canine Cancer Campaign supports. As an introduction, here are some early warning signs owners can watch for in their dogs.
The American Veterinary Medical Association has developed the following list common signs of cancer in small animals.
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Abnormal swellings that persist or continue to grow
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Sores that do not heal
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Weight loss
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Loss of appetite
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Bleeding or discharge from any body opening
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Offensive odor
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Difficulty eating or swallowing
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Hesitation to exercise or loss of stamina
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Persistent lameness or stiffness
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Difficulty breathing, urinating, or defecating
Any of these signs could be present in a dog with non-neoplastic (non-cancerous) diseases as well. Brief comments about each follow, but these comments are offered only as food for thought. It is never wise to ignore any of the warning signs.
Abnormal swellings that persist or continue to grow certainly should be evaluated by a veterinarian. Either might represent a benign condition such as hyperplasia (overgrowth of normal tissue), a vaccination reaction, or a foreign body associated with chronic inflammation, but the possibility of serious malignant disease should not be lightly discounted.
Sores that do not heal might also be the result of some non-malignant chronic inflammation or self-trauma. Nonetheless, non-healing sores are quite likely to represent an underlying cancer and should be investigated. In either instance, a biopsy will likely be needed to resolve the question of the underlying cause.
Weight loss and loss of appetite are both non-specific signs that might signal a wide variety of diseases in various body systems. The definitive diagnosis with such vague presentations may be elusive and may require a good deal of diagnostic work.
Similarly, hesitation to exercise and loss of stamina are both quite non-specific signs. Middle-aged to older dogs, the very population most at risk for cancer, may demonstrate these signs simply as a matter of aging. Again, prompt and thorough evaluation by your veterinarian is key to finding out the cause.
Other signs including difficulty eating or swallowing, persistent lameness or stiffness, bleeding or discharge from any body opening, and difficulty breathing, urinating, or defecating more directly point to a particular body system. However, finding the site of a problem does not constitute a diagnosis. Similarly, an offensive odor may be a localizing sign that has a non-neoplastic cause such as an ear infection, dental disease, or problems with the anal sacs, but at any of these locations the real problem may be cancer.
Over the years, better care, including improved nutrition and vaccination programs for dogs, has increased life spans and allowed more dogs to reach the ages at which cancer incidence increases. It has been estimated that 50% of dogs over ten years of age will, in fact, die of cancer. Early detection at yearly or semi-annual routine examinations is important, but the warning signs discussed here will be seen by owners almost always before they are picked up on routine wellness checks. Be aware of them and you can help your dog by seeing that the correct diagnosis is made as early as possible.