The following information covers some of the more common drugs used at home to treat cancer. Which drugs are used will depend both on which disease your pet has and what other therapies are being pursued. If you have any questions about the medications here, please talk to your doctor or a staff member.
Most people have had experience with cancer and cancer therapy, whether it is personal experience, with a family member, or through a close friend. Often, these experiences are not pleasant, despite having positive rewards at the end. Cancer in veterinary medicine, though, is treated differently than in human medicine. Our goal in veterinary medicine is not to achieve a “cure” but to achieve the best quality of life for our patients. We may be able to achieve a remission (different than a cure) with some diseases, but for others we aim to stop or slow down growth.
When a pet experiences a side effect from chemotherapy, it typically starts the second or third day after treatment. This period, from three to five days after treatment, is when symptoms occur with the GI tract. The bone marrow can have problems as early as day three but it is typically six to eight days after when cell counts are at the lowest. If white blood cells get too low, opportunistic microbes can get a hold and make pets feeling sick. Symptoms can include problems with the GI tract as well as decreased energy and generally “not feeling well”.
Most of our patients (greater than 90%) will have absolutely no side effects from chemotherapy. That is unless you want to include feeling better and happier with the side effects. For the majority of our patients that receive therapy and have a response, this will be the only “side effect” they experience.
Of the remaining 5-10% than develop side effects, most will be mild in nature and easily controlled from home. The most common side effects reported include loss of appetite, low energy, nausea, diarrhea, soft stool, and vomiting. To help treat these, we send home medications for you to have on hand in case side effects occur. Typically, cats will get upper GI side effects (nausea, vomiting, and loss of appetite), while dogs can experience the whole range of symptoms. The medications can be used prophylactically (starting the night of therapy) or held in reserve and used only if symptoms occur. It is important to use these medications at the first sign of symptoms. If started early, side effects can be stopped before they become more serious. The medications we send home are safe to use and will not cause your pet any issues if they are given them but did not actually need them.
A small number (1-2%) of pets will require more intensive care to control their symptoms. This includes outpatient injectable medications or inpatient hospitalization with IV fluids and injectable medications. This typically occurs when the symptoms come on suddenly and at home medications are not adequate to control them, or due to an overwhelming response of the cancer to therapy that “floods” the body with dead cancer cells. This can cause your pet to feel sick while the body plays catch –up in filtering out the dead cells. If symptoms are not addressed quickly, your pet’s condition can deteriorate rapidly. In extreme situations, a pet can have a fatal event after receiving therapy, usually from suppression of the bone marrow (low cell count), compromised body systems (like kidney or liver), or untreated symptoms (vomiting, diarrhea, etc). If your pet is not responding to medications at home or has severe symptoms that come one suddenly, please seek immediate care here, your regular vet, or your local emergency center.
Ultimately, the primary goal of veterinary chemotherapy protocols is to provide good quality of life for our patients while managing the cancer for as long as possible. Thus, if a pet has a side effect we switch drugs, adjust doses, or stop treatment entirely. We do not want our patients getting sick any more than you want your pet to be sick. If you have any questions or concerns about sick effects and your pet, please feel free to discuss these with your doctor.