Chemotherapy. Just the word alone may conjure up negative images but animals respond differently. Don’t let negative connotations prevent you from pursuing a cancer treatment that can be potentially lifesaving for your pet.

What is chemotherapy?

Chemotherapy may sound like a scary word, but really it just means using medication (as opposed to surgery or radiation) to treat cancer. When cancer is not localized to one specific area, it is difficult to remove surgically or kill the cells with radiation. But we can use the same blood vessels that feed the cancer cells to poison them using intravenous or oral medications. This is chemotherapy.

The target of chemotherapy drugs is cells that are rapidly dividing, which describes most cancer cells. We count on chemotherapy to kill these types of cells while leaving the surrounding normal cells intact. Unfortunately, some normal cells in our bodies also rapidly divide, including cells in the bone marrow, digestive tract, and hair follicles. This can lead to side effects.

Side effects of chemotherapy in pets

Fortunately for our canine and feline friends, side effects are much milder. We can add anti-nausea medications to your pet’s therapy to combat post-chemotherapy nausea.

Bone marrow suppression does occur in animals. The bone marrow is the source for all blood cells, both red and white. Because white blood cells are key in fighting off infections, when their numbers decline, your pet will be more prone to infections.

Most pets do not experience hair loss, but they can lose their whiskers, which may or may not grow back. And it may take some time for hair that is shaved to grow back. But for most pets, massive hair loss just doesn’t occur. The exception to this is breeds of dogs who have synchronous hair follicle activity, like Poodles, Shih Tzus, Lhasa Apsos, and Old English Sheepdogs, to name a few.

So, now that we’ve covered the hard facts of chemotherapy in pets, it’s time to address some of the “soft” facts. Mainly, is chemotherapy right for your family? Of course, this is a deeply personal question, and there is no right answer. You have to take into consideration many factors before deciding for or against chemotherapy.

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Sometimes, it just doesn’t make sense to pursue chemotherapy. Either because the cancer your pet has doesn’t respond well, or because your pet’s prognosis is grave even with chemotherapy.


Chemotherapy is expensive. Not only because the drugs themselves are expensive, but also because your pet will likely need to be hospitalized for treatment each time. Courses of chemotherapy will vary in the number of visits your pet will need and the total length of therapy. Luckily Petplan pet insurance covers all cancer treatments, but if you do not have a policy for your pet, you could be looking at thousands or even tens of thousands of dollars in treatment costs.

Your pet’s disposition

Because your pet will need to be hospitalized for what may be weekly visits, it might not make sense to pursue chemotherapy in pets that are very uncomfortable in the hospital. In general, most pets acclimate well but some pets just don’t do well in that environment and it may not be fair to them to pursue chemotherapy.

Your veterinarian or veterinary oncologist (or both!) will be more than happy to address your questions or concerns. They can tell you about their experiences with similar cases of cancer.

Chemotherapy gives your pet a chance to beat cancer, or at least send it into remission so they can get on with their regular lives – whether that means chasing a Frisbee or just lounging in the windowsill soaking up the sun. If your pet is facing a diagnosis of cancer, ask your veterinarian if chemotherapy can help.

Sep 18, 2013
Pet Health

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