Common Veterinary Chemotherapy Questions & Answers


Chemotherapy is the general term for any treatment involving the use of chemical agents to treat a specific disease. However, it is generally associated with cancer treatment. Chemotherapy can eliminate cancer cells at sites great distances from the original cancer. As a result, chemotherapy is considered a systemic treatment. Chemotherapy can be administered through a vein, injected into a body cavity, or delivered orally in the form of a pill, depending on which drug is used. Some cancer cells grow slowly while others grow rapidly. As a result, different types of chemotherapy drugs target the growth patterns of specific types of cancer cells. Each drug has a different way of working and is effective at a specific time in the life cycle of the cell it targets. Chemotherapy may be used as the sole treatment for certain cancers or may be used in combination with other treatment modalities, such as surgery and radiation therapy. Chemotherapy is likely to be recommended for cancer that has already spread to other areas of the body (metastatic disease), for tumors that occur at more than one site (multicentric disease), or for tumors that cannot be removed surgically (non-resectable disease).

Questions and Answers on Chemotherapy Treatment

Can my pet eat before chemotherapy?
Yes, your pet can eat prior to chemotherapy treatment. However, occasionally, certain testing might require fasting. We will inform you before your appointment if fasting is necessary.

Will my pet lose hair with chemotherapy treatment?
Hair loss is not likely to occur. Certain breeds, such as cocker spaniels, poodles, and terriers, that are groomed often, may loose some hair because of their rapid hair growth rate. Shaved areas will grow back slowly. Cats may lose their whiskers. The hair will re-grow once the treatments have finished. Occasionally, hair will grow back a different texture or color. This is a cosmetic side effect and does not impact the quality of your petís life.

Is chemotherapy toxic?
The overall toxicity rate is very low in veterinary cancer patients who undergo chemotherapy. The treatments oftentimes are not dose intense and our primary goal is to provide the best quality of life possible for as long as possible.

Chemotherapy drugs attack rapidly dividing cells in the process of growth and division. All rapidly dividing cells are potentially sensitive to chemotherapy. The normal tissues that typically are most sensitive to chemotherapy are the intestinal lining, the bone marrow (which makes red and white blood cells), and hair follicles. Although less likely to occur, clinical signs of illness vary from slight decrease in energy and appetite to lethargy, anorexia, diarrhea and vomiting, fever, or mild hair loss. Typically, over-the-counter medications can be used if side effects occur. These side effects are medically manageable. In our experience, there is less than a 5% chance that your pet will need hospitalization for medical stabilization with fluids and IV antibiotics. If any of the above side effects are noted, the drug type or dosage will be modified to minimize the chance of side effects recurring.

When a chemotherapeutic drug is used that is known to have a high potential for bone marrow suppression, a complete blood count (CBC) is checked several days after the treatment. If the white blood cell count is low but your pet is felling well, antibiotics are prescribed as a preventive measure. Subsequent doses of chemotherapy are adjusted based on the results of the CBC.

What precautions are needed for drug handling at home?
Keep all oral medications out of the reach of pets and children.

If you are pregnant, trying to get pregnant, or nursing, try to arrange for someone else to administer the prescribed medication. Most oral drugs have a protective coating, but we recommend that latex or polyvinyl gloves be worn when handling these medications.

It is very important to not tamper with the medication. Do not cut tablets or open capsules, as this will increase the exposure to the medication. While there are no set guidelines, we recommend that you do not come in direct contact with your petís urine or stool for 72 hours following chemotherapy.

Should I vaccinate my pet under chemotherapy treatment?
While undergoing cancer therapy it is possible that your petís immune system is compromised either due to cancer itself or by chemotherapy. We do not recommend vaccinating your pet during chemotherapy. We recommend waiting for a scheduled break in the chemotherapy before resuming vaccinations. Please contact us before any vaccines are given. We do prefer that your pet is current on rabies vaccination, as this is public health concern.

Prednisone or Prednisolone
Prednisone is a glucocorticoid steroid medicine. Glucocorticoids hormones are produced naturally by the adrenal glands. The medicine is prescribed for various reasons ranging from use as an anti-inflammatory, appetite stimulant, and immune system suppression to some forms of cancer. Long-term use of prednisone can cause side effects such as liver and kidney toxicity, muscle wasting, weight gain, generalized weakness, and so on. The most common side effect noted early on is excessive thirst and excessive urination. Glucocorticoid hormone use can be irritating to the stomach at higher doses. We prefer this medicine to be administered in the morning with food.

Glucocorticoid hormones should not be used in combination with medications of the NSAID class (i.e., aspirin, Rimadyl, phenylbutazone, and so on) as the combination of these medications could lead to bleeding in the stomach or intestine. Ulceration could occur. It is important that after 2 weeks or more of use, the dose should be tapered to an every other day schedule so as to keep the bodyís own cortisone sources able and healthy.

Remember when giving Prednisone or Prednisolone
Administer with food.
Do not discontinue this drug without a slow taper of dose reduction.
Keep fresh water available at all times.