Editor’s note: This is the second column in a two-part series. Visit www.vaildaily.com to read the first installment.
In this past week’s article we discussed some signs and symptoms of cancer and how we diagnose them. Now, let’s move on to some of the more common cancers and how to treat them.
Basically you have three choices for therapy: Cut it out (surgery), poison it out (chemotherapy) or burn it out (radiation therapy). Without being flippant, that is exactly what we are going to do. Dr. Greg Ogilve, Colorado State University’s animal cancer guru, advocates surgery as the first line of treatment and says: “when in doubt, cut it out” and “your best deal is cold blue steel.”
For some cancers, surgery is all that is needed; others require chemotherapy to prevent spread, called metastasis, and still others require radiation therapy. Sometime a combo of chemo and radiation is used. Often times a tumor cannot be removed or it is too large to remove so we try chemo or radiation to shrink the tumor to a more manageable size, and then remove it.
Other cancers need chemo to control them, for example lymphoma (cancer of the lymph nodes) or leukemia (cancer of the white blood cells) cannot be treated surgically. Staging, or determining how widespread the cancer is, will tell us what type of chemo to use and for how long.
Yes, chemo is a scary word but pets tolerate it a lot better than we do. I would say more than 95 percent of the owners who have had me do chemo on their pets would do it again if needed. Dogs rarely loose their hair (except maybe whiskers) and usually only have a day or two of nausea between cycles.
Phases of Chemo
There are two phases to chemo: the induction phase, which is rigorous and done weekly until the cancer is in remission; then a maintenance phase is started where a round of chemo is given every 3 to 4 weeks until all the cancer is gone. Chemo routines, called “protocols,” are changing all the time; the line between where induction ends and maintenance begins is a hot topic today.
Radiation therapy is done much less in my experience because it must be done very frequently; often up to 3 times a week. For us that means going to Denver (and as I write this, I-70 is closed eastbound).
Let’s move on to some common cancers. Breast cancer in female dogs is very common and a good example where surgery alone can be curative. This cancer is almost 100 percent preventable by spaying your female dog before her first heat cycle. If the cancer is malignant or advanced, then radiation is the preferred method to prevent spreading; however, I have used chemo successfully. Mast cell tumors are a common dog skin tumor and need to have a very wide and deep surgical excision, therefore a pre-op needle biopsy should be done. This tumor should be sent of to a pathologist to grade, from 1 to 3, to tell us the degree of malignancy as this will dictate what or even if chemo is needed. Other common canine cancers are lymphoma, bone cancer, intestinal cancer and oral cancers.
Cats are also prone to cancer. Breast cancer is much more serious in cats than in dogs as almost all are malignant, whereas only half are malignant in dogs. In one large study of 439 cats, only 8 percent had benign tumors (meaning 92 percent were malignant). Early spaying is recommended but we can’t say for certain if it prevents breast cancer in cats. Skin tumors are also more malignant in cats than dogs so if you see bumps on your cats, get them checked out. Intestinal cancer is also more common in cats than dogs.
Treating cancer can be expensive but it is rewarding for both veterinarians, pet owners and life extending for pets. Just ask my last case, Maya, who can be seen walking around Eagle!
Veterinarian Stephen Sheldon, a member of The Veterinary Cancer Society, practices at Gypsum Animal Hospital. He welcomes your questions and can be reached at 970-524-DOGS or www.gypsumah.com and firstname.lastname@example.org.