Cancer is often unpredictable, and as a result, may require a variety of treatment modalities. As with people, surgery, radiation therapy, and chemotherapy are commonly used alone or in combination with other treatments to control cancer in pets. Chemotherapy may be used to treat cancer that has spread to other parts of the body, to treat cancer that cannot be treated with surgery or radiation therapy alone, or when it may enhance the effectiveness of these treatments. Chemotherapy treatment for pets with cancer is supervised by a medical oncologist, a veterinarian with five years of specialty oncology training. Flint Animal Cancer Center’s medical oncologists are board-certified and specially trained to diagnose cancer in pets and prescribe treatment while monitoring for side effects and making the appropriate adjustments to ensure each pet patient maintains a good quality of life.

The prospect of chemotherapy for your pet may be intimidating or even scary. The good news is that pets typically handle chemotherapy much better than people. Knowing how chemotherapy drugs work and what to expect from the treatments can help you decide whether this therapy is right for your pet. The following represent some of the most common questions relating to chemotherapy for pets with cancer.

What is chemotherapy?

Chemotherapy is drug therapy designed to kill or slow the growth of cancers. Many of the drugs used to treat cancer are derived from natural substances such as plants, trees or even bacteria and are often the same drugs used in people. Some drugs have a broad spectrum of activity, while others are more targeted.

When do we use chemotherapy to treat pets with cancer?

Chemotherapy may be used as the primary treatment for certain cancer types, or may be used in combination with other treatments such as surgery and radiation therapy.  In some cases, chemotherapy can be used to try to shrink large tumors prior to surgery, or to help eliminate microscopic cancer cells that cannot or have not been completely removed surgically.  For cancers that are at high risk for spread, chemotherapy can be used after surgery to help delay or prevent the appearance of cancer in other parts of the body.

 What is the goal of chemotherapy?

The goal of chemotherapy is to control or eliminate the cancer while still providing the highest quality of life to your pet. Chemotherapy drugs sometimes do not cure cancer but rather control the cancer by killing cells and slowing the progression of the disease.

How is chemotherapy given?

There are different formulations of chemotherapy. Some drugs must be given intravenously (IV), others may be given under the skin or into a muscle. In some cases the drug may be injected directly into the tumor itself. Some chemotherapy can be given orally in pill form.

IV drugs: Such as vincristine or doxorubicin; an intravenous catheter must be placed for safe administration of the drug. After administration, the catheter is removed and a light bandage is placed. The “band-aid” can be removed 1-2 hours after the drug is administered.

Oral drugs: Oral drugs are administered by you at home. It is important that your pet receive all medications as prescribed and that the pills are not crushed or split, nor capsule opened. It is sometimes helpful to coat the pills with butter, peanut butter or cream cheese to make it more appealing for your pet. If you are administering an oral chemotherapeutic drug, you will be given latex gloves to wear while you handle these pills. When you are finished giving the pills, wash your hands to remove any medication residue from your skin.

What sort of side effects may my pet have with chemotherapy?

The highest quality of life for your pet is our goal, but to be effective in controlling a devastating disease like cancer, chemotherapy drugs are very powerful. Fortunately, pets don’t have as many side effects as humans going through chemotherapy do. In fact, 70% of pet patients face few, if any side effects. Hair loss (alopecia), is common in humans but rare in dogs. It is seen mainly with breeds that have constantly growing hair (poodle, shih tzu, cocker spaniel, etc.). Cats generally do not lose body hair, but often lose their whiskers. Chemotherapy will slow the re-growth of hair in all pets receiving chemotherapy so grooming schedules may need to be adjusted accordingly. Other potential side effects include nausea, vomiting, diarrhea – most of which are readily controlled with medications / diet change and only last for a day or two. A common side effect with many chemotherapy treatments is a decrease in the white blood cell count. This could make your pet more susceptible to contracting infections if the decrease is severe. At the Flint Animal Cancer Center, we routinely check the blood cell counts before every chemotherapy treatment to insure that the white blood cell count is not dangerously low.

How should I handle body fluids while my pet is on chemotherapy?

Do not handle feces, urine or vomitus unless absolutely necessary within 24 hours of the chemo administration. If your pet has an “accident”, wear gloves and clean the area with disposable items (paper towels, baby diapers, etc.) and dispose in the trash. Wash your hands thoroughly when you are finished cleaning. In general, it is recommended that clothing/ bedding which is soiled by feces, urine or vomitus within 24 hours of chemotherapy administration should be washed twice in hot water.

How often is chemotherapy given?

Some drugs are given daily, others weekly and some only every 2-3 weeks. Your time commitment will depend on the chemotherapy drug protocol you choose to treat your pet with.

What is a chemotherapy drug protocol?

The word protocol refers to a set regime of drug(s) given in a specific time frame. This may incorporate one or multiple drugs.

How long will my pet receive chemotherapy?

Many chemotherapy protocols involve a series of treatments, followed by a period of careful observation. However, in some patients with advanced disease, chemotherapy may be continued as long as it is controlling the cancer.

What happens when chemotherapy no longer controls the cancer?

Cancers can be initially very sensitive to chemotherapy drugs. Unfortunately, the cancer may return weeks, months or years later. In such cases, the cancer cells have become resistant to the drugs in a similar way bacteria become resistant to antibiotics. When resistance to one drug occurs, we can often use other drugs. However, each time resistance develops it becomes more difficult to find a drug that the cancer will respond to. In some cases, cancer develops resistance to all drugs. At this point, your pet’s clinician will discuss with you ways to keep your pet comfortable for the remainder of his/her life.

Flint Animal Cancer Center Medical Oncology

The Flint Animal Cancer Center oncology service includes four medical oncology faculty, five medical oncology residents, one medical oncology intern, and a team of veterinary technicians. They work with surgical and radiation oncologists to determine the best treatment plan for each pet cancer patient.  The Flint Animal Cancer Center is one of the few veterinary oncology services in the world to offer a comprehensive model of care.