We regularly get questions from dog owners at our Ask A Pet Pro blog about canine lymphoma, an increasingly common form of cancer.
Today we received an email from the University of Illinois College of Veterinary Medicine that we’d like to share with you.
Canine Lymphoma
Author: Ashley Mitek
An archive of Pet Columns from the University of Illinois College of Veterinary Medicine is available online at www.vetmed.illinois.edu/petcolumns/. Requests for reprints of this article may be directed to Mandy Barth, mandyb@illinois.edu.Approximately 5 percent of all human cancers in the United States are diagnosed as lymphoma according to the National Cancer Institute. Unfortunately, it is much more common in our canine companions. Nearly 20 percent of all reported malignant tumors in dogs are lymphoma. The disease, which starts in the lymphocytes (white blood cells) of the immune system, can go on to invade the lymph nodes as well as almost any other part of the body.
Dr. Laura Garrett is a veterinary oncologist at the University of Illinois Veterinary Teaching Hospital in Urbana. She says, “lymphoma usually affects middle-aged to older dogs. But it is also one of the few cancers that commonly affects young dogs as well.”
In contrast to the feline forms of lymphoma, there is no known cause of the cancer in dogs. However, some breeds seem to be predisposed, such as: golden retrievers, Scottish terriers, mastiffs, and rottweilers. The disease also presents differently in dogs. While cats with lymphoma are typically very ill by the time they see a veterinarian, dogs with lymphoma usually do not feel sick when they are diagnosed.
“Dog owners usually complain of lumps under the jaw,” explains Dr. Garrett, or a veterinarian may notice them on a routine physical exam. The “lumps” that can be felt are enlarged lymph nodes. As lymphoma spreads, it has the ability to affect lymph nodes all over the body, as well as other organs. This type of lymphoma, called “multicentric,” reflects the fact that it is found in multiple places. It is the most common form of the disease in dogs.
Because lymphoma is a cancer that tends to be very widespread throughout an animal’s body, there is only one real choice of therapy that has the potential to make the cancer go into remission: chemotherapy.
“Lymphoma is not a surgical disease,” notes Dr. Garrett. The only way oncologists can attempt to slow down its progression is to try and poison the fastest growing cells in the dog’s body (usually the tumor cells) with chemotherapy.
Thankfully, dogs with the multicentric form of lymphoma have a good to excellent chance of responding well to treatment. That said, there are other forms of the disease, such as the gastro-intestinal variety, that do not respond very well to therapy, so it is important to know what kind of lymphoma you are dealing with.
In general, dogs with the multicentric form of lymphoma will live approximately one year after being diagnosed if they have completed chemotherapy. If owners choose not to treat, dogs can expect to live around four to six weeks after being diagnosed.
It is important to note that each patient with lymphoma is different, and the median survival time is simply that–an average that can be used to help inform owners. Depending on certain prognostic factors, patients may be more likely to do better or worse. For example, a dog that is not feeling well at the time of lymphoma diagnosis is a very strong negative prognostic indicator. Meaning, the animal is much worse off than a dog that feels well at the time of diagnosis.
For information regarding lymphoma, contact your local veterinarian. A list of board certified veterinary oncologists in your state can be found by visiting Veterinary Cancer Society Web site: http://www.vetcancersociety.org/.
Source: Dr. Laura Garrett, DVM, DACVIM
