Dog Owner's Home Veterinary Handbook.pdf - Mr. Walnuts

528 •DOG OWNER’S HOME VETERINARY HANDBOOK
cell carcinomas, cancers of the oral and nasal cavities, and soft tissue sarcomas.
A potential disadvantage of radiation therapy is that it requires special equipment
and must be done at a medical center. Radiation therapy can also be
done to relieve pain, especially with very painful cancers such as osteosarcoma
(bone cancer).
Chemotherapy is used to prevent and control the metastatic spread of cancer
cells. However, most canine cancers are only moderately sensitive to
chemotherapy. It can cure only one type of cancer in dogs: transmissible venereal
tumors. When used as the only form of treatment, chemotherapy usually
does not extend survival. Lymphosarcoma and leukemia are exceptions.
Chemotherapy drugs, even when their use is tightly controlled, can have
major side effects. In humans, chemotherapy is aimed at achieving a cure.
Due to their lesser efficacy in dogs, chemotherapy is aimed at controlling the
disease and giving the dog a period of remission. Lower dosages are generally
used and many dogs do not have the severe reactions to chemotherapy that
people do.
Chemotherapy may include such new methods as injecting a photosensitive
substance that is attracted to cancer cells. Light therapy then causes the
destruction of those cells.
Immunotherapy using interferon, monoclonal antibodies, and other agents
that stimulate the immune system is receiving renewed interest and has the
potential to become an important treatment option. Immunotherapy has
been used successfully to extend survival time in dogs with late-stage lymphosarcomas
and mast cell tumors. (Prednisone has also been used successfully
in combating these cancers.) Newer work is looking at vaccines for
cancers, and this area shows quite a bit of promise.
A combination of the treatment methods (for example, surgical excision
followed by radiation or chemotherapy) is often more effective than surgery
alone. This is true for osteosarcoma. Only those treatments known to be
effective against a particular cancer should be considered for combination
therapy.
FINDING TREATMENT
It makes sense if your dog has cancer to seek out a referral center that routinely
deals with cancer cases. But that is sometimes easier said than done.
Most veterinary schools and other referral centers have a veterinary oncologist
on staff. These veterinarians may offer treatments at their facility or confer
with your veterinarian on treatments such as chemotherapy regimens.
Most of these referral centers are also conducting research and may be
looking for patients with a specific disease to be involved in clinical trials.
Being included in a cancer study can help with expenses, give you access to
the latest techniques, and possibly help other dogs in the future.