Chemotherapy and Your Dog

When dogs get cancer, they may be treated with chemotherapy and/or radiation, just like people are. People are usually in shock when they find out their dog has cancer, and it can be hard to take all the information offered in at once. This article discusses chemotherapy, radiation, and the veterinary professionals that treat cancer with these methods.

Chemotherapy can be given orally, through an IV, with a shot to the belly, and many other ways. The reason for chemotherapy is obvious — to save the dog. However, there are different kinds of chemotherapy that are given to the dog with different goals.

Adjuvant chemotherapy is given to the dog after surgery removes the tumor. Its purpose is to kill any cancer cells that were accidently left behind during surgery. Most of the time, it is impossible to get all of the cancer cells because they cannot be seen with the naked eye. Adjuvant chemotherapy seeks them out and kills them before they can spread.

Neoadjuvant chemotherapy is given before surgery is performed to shrink the size of the tumor and make it easier to take out. This method of chemotherapy is rarely used with dogs. The exception is with mass cell tumors, which can be shrunk and then removed easier.

Induction chemotherapy is used to bring the cancer into remission. This is the treatment of choice for dogs with blood borne cancers. Induction chemotherapy may be combined with maintenance chemotherapy to keep the cancer in remission.

Chemotherapy is considered to be the first line of defense when the dog is treated with drugs that have been tested and approved for that type of cancer.

Chemotherapy is considered “second line” when the first line chemotherapy does not work or the cancer comes out of remission while the dog is still taking the first line chemotherapy.

Radiation is the use of ionizing radiation to treat cancer. It is usually done by a large machine, but can be done with a handheld device, by implanted bits of radioactive metal, or orally by drinking a radioactive substance.

Regardless of how it is administered, the goal is to kill the cancer. Your dog must be in the same exact position every time the radiation is administered, so he must be anesthetized for each session. Also, markings are put on the dog’s body to show the treatment personnel where to aim the radiation machine.

Chemotherapy can be administered at the same time as radiation to increase the effectiveness of the radiation. The dog must be monitored closely as the side effects can be pronounced.

Your local veterinarian will probably not have the chemotherapy medication or the radiation machines to effectively treat your dog. He will most often refer you to a medical oncologist to manage the chemotherapy and a radiation oncologist to manage the radiation portion of the treatment. While medical oncologists learn the principles of radiation, and may manage the radiation portion of the treatment, they are not considered board certified radiation oncologists. Radiation oncologists may manage the chemotherapy part of your dog’s treatment, but are not considered board certified in chemotherapy.