Chemotherapy and you pet

The use of chemotherapy depends on several factors, including the type and location of the tumor, the condition of the patient and whether the tumor has spread to other organs, as well as personal decisions such as financial constraints. Chemotherapy may be used alone or with surgery or radiation therapy, depending on the tumor type and its location. Positive responses to chemotherapy range from partial remission and slowing progression of the disease to complete remission. Most cancers are not completely cured by chemotherapy and many recur at some time in the future.

Chemotherapy works by damaging rapidly growing cells. Rapidly dividing cancer cells are typically more sensitive to chemotherapy than normally dividing healthy cells. The effective use of chemotherapy is a balance between killing cancer cells and minimizing side effects that arise from killing healthy cells in the patient.

Chemotherapeutic agents are commonly admini-stered together in specific protocols that maximize destruction of tumor cells but minimize side effects to the patient. Most veterinarians consult with veterinary oncologists concerning which protocols are best used against which cancers. Discuss your pet’s protocol with your veterinarian to be sure you understand possible side effects, the treatment schedule and costs, as well as the monitoring and follow-up care required. Many chemotherapy treatments can be given at the hospital over a few hours. Laboratory tests are often checked before chemotherapy is given.

Chemotherapeutic drugs affect the fastest dividing cells in the body, which include not only cancer cells but also some healthy cells, especially those of the bone marrow and gastrointestinal tract. Common side effects include a low white blood cell count, a low red blood cells count, nausea, vomiting, diarrhea and a decreased appetite. Pets rarely lose their hair as human patients undergoing chemotherapy do. Since lower doses of chemotherapeutic drugs are used in animals than in people, pets tend to tolerate chemotherapy much better than people do.

Careful monitoring is required to check for side effects of chemotherapy, to monitor effects of the medications on other organ systems, to monitor the response of the cancer to the chemotherapy and to watch for spread of the cancer. Monitoring usually requires repeated physical exams, laboratory tests, X-rays and abdominal ultrasound exams.


Dr. Karsten Fostvedt is a veterinarian at St. Francis Pet Clinic in Ketchum.

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