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Cancer is a common canine concern, affecting an estimated 25% of all dogs and 30% over the age of 7, according to the AKC Canine Health Foundation (CHF). Unfortunately, for many dogs, the disease can be fatal. For older pets, it’s the leading cause of death, with as many as half dying from cancer.

The shock of a cancer diagnosis for your pet can bring with it a lot of questions. What options are there for dogs with cancer? Is chemotherapy one of them? What’s involved? To answer these and other frequently asked questions about dog chemotherapy, or chemo for short, we spoke with Diane Brown, DVM, Ph.D., DACVP, the Chief Executive Officer and Chief Scientific Officer of CHF.

What Is Chemotherapy?

As with humans, chemotherapy for dogs is a series of drug treatments intended to help eliminate or slow the growth of cancer.

How Does Chemotherapy Work?

With the goal of clearing up cancer or preventing it from spreading, chemotherapy treatment works by attacking growing cells. The treatment targets cells, whether they’re cancerous or not, and is meant to either kill the cells or stop them from dividing.

Yorkshire Terrier laying down in its bed.
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How Is Chemotherapy Given to Dogs?

Your veterinarian may offer chemotherapy alone or along with other interventions, such as surgery or radiation. Drugs may also be given orally as a pill your dog can swallow. A veterinarian may administer chemo via an injection at an appointment, according to OnCoLink, a cancer website produced by oncology health professionals. In some cases, your pet may have to stay at a hospital for treatment.

How Long Does Chemo Treatment Last?

“It’s very individualized based on the type of cancer, the stage, and the treatment that’s recommended,” says Dr. Brown. “So, there’s no single one answer.”

There’s also not a single answer to the question of cost, as this may vary by type of cancer and stage. Some dogs may stay on chemo for the remainder of their lives. Others may receive sporadic treatment or end treatment altogether if their cancer clears up or goes into remission.

Golden Retriever getting comforted while lying on a table at the vet.
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How Does Chemotherapy Affect Dogs?

Some common side effects of chemo on humans, like nausea, vomiting, and low energy levels, are well known. Because dogs usually receive lower doses of the treatment and fewer additional drugs, they may experience milder reactions to taking chemo. For example, most breeds typically do not lose their hair like people do.

Dogs may experience some mild, moderate, or severe appetite loss, vomiting, or diarrhea. Decreased white and red blood cell counts may lead to a greater risk of infection. Lastly, some dogs may experience lethargy due to the treatments. If your dog experiences any clinical signs that seem out of the ordinary, you should discuss these with your veterinarian.

How Does Chemotherapy Affect a Dog’s Survival Chances?

“Many factors influence a dog’s chances of survival after a cancer diagnosis. These include type and stage of cancer, the exact chemotherapy/treatment protocol chosen, and other health factors,” explains Dr. Brown.

Your pet has the greatest chance of survival from cancer if the illness is detected while still in an early stage. Indeed, early detection can help with treatment, recovery, and prolonging your dog’s quality of life.

Cancer is, unfortunately, often incurable in dogs. In these cases, your veterinarian may still recommend chemo as a way to help ease your pet’s symptoms resulting from the disease.

When Is Chemotherapy Recommended?

A veterinarian or a veterinary oncology specialist will recommend treatment options based on the type, grade, and stage of cancer. These and other factors will also help determine if other treatment options, such as surgery, radiation, immunotherapy, complementary therapies, or a combination of therapies, are a fit, explains Dr. Brown.

Senior Labrador retriever laying down indoors.
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Determining What’s Best for Your Dog

Learning about cancer and chemo can be overwhelming and raise a lot of questions. To ensure you get all the answers you’re looking for, Dr. Brown recommends the following:

Make sure you receive a definitive diagnosis. This will involve testing (such as X-rays and a biopsy), getting results, and determining if additional diagnostic testing is necessary (such as an MRI).

Figure out a timeline for making decisions. In some cases, there may not be much time to research your options. Therefore, make sure you have a plan in place for different scenarios.

Get all the guidance you need. One way to do this is by having open discussions with your veterinarian. Additionally, consider seeking counsel from a canine oncologist.

Learn from others going through the same thing. Support groups may be available near you for families with dogs with cancer.

Learn what your dog’s quality of life will be like: Does your dog have other health issues, like heart or kidney disease? Ask about these and other factors that may impact your dog’s overall comfort.

At the end of the day, there’s no perfect answer to these and other questions. According to Dr. Brown, the best you can do is to consult with experts for advice, including your veterinarian or veterinary oncologist, ask questions, educate yourself, and consider options from your veterinarian on how you can best care for your dog.

Related article: Everyday Ways to Reduce Cancer Risk for Your Dog