Chemotherapy for Dogs: Everything You Need to Know

By Carol McCarthy

“Your dog has cancer” might be the four scariest words a pet parent can hear. After you get that diagnosis, chances are you scarcely hear your vet lay out the treatment options, which likely include chemotherapy. Understanding exactly what this treatment is and how it works, however, will ensure that you make the best decision for your dog. Learn more about what chemotherapy for dogs is, how much it may cost, and what the process will be like for your pet, below.

What is Chemotherapy and Why Would My Dog Need It?

Chemotherapy is a term given to a group of drugs that have the ability to kill cancer cells in dogs. The specific medication or combination will depend on the type of cancer your dog has, as well as his overall health. Your vet will monitor the chemotherapy treatment to ensure that it is working well with minimal side effects. If not, he or she might try another drug or change the dosage and frequency.

Chemotherapy is often prescribed for one of the most common cancers in dogs, lymphoma, as well as for some other malignancies.

“Chemotherapy is recommended for cancers that either have already spread to other areas of the body (metastasized) or are known to have a high potential for metastasis,” said Dr. Lisa Barber, assistant professor of oncology and chemotherapy at Tufts University’s Cummings School of Veterinary Medicine.

Dr. Joanne Intile, staff oncologist at the East End Veterinary Emergency and Specialty Center in Riverhead, N.Y., said that the use of chemotherapy depends on the type of cancer and other factors. “The ultimate recommendation depends on whether it is a single tumor on the skin, whether we can do surgery, if it is more widespread or the dog isn’t a good candidate for surgery,” she said.

If surgery is advised, the doctor will remove the cancerous tumor. The tissue containing the cancerous cells will be sent to a laboratory where a pathologist (a veterinary specialist) will examine the cells under a microscope. The pathologist will look at the edges of the cancerous tissue to determine if they are likely to regrow in that location and will grade the cancer on its likelihood for metastasizing. Cancers considered “high grade,” that is, those that have the likelihood to metastasize, often are treated with chemotherapy, Barber said.

The goal of chemotherapy in animals is different than for humans, which is why treatment is less aggressive. With pets, the primary goal of chemotherapy is to provide your cat or dog with the best quality of life for as long as possible.

“We hope for a cure,” Intile said. “But we don’t see a lot of cures because we don’t treat them as aggressively. Their quality of life is most important. Unlike human oncology, it’s quality-of-life [treatment], not life-at-all-costs [treatment].”

How Much Does Chemotherapy for Dogs Cost?

As with any medical treatment, chemotherapy cost can vary widely depending on the frequency and duration of the treatment, the drug(s) used, the medical facility and geographic location.

“At Tufts, a standard chemotherapy protocol for lymphoma is likely to cost $3,500 to $4,500. At other clinics, the cost can be $10,000 or higher,” Barber said. A commonly referenced standard treatment for this type of cancer is the Madison Wisconsin Protocol, which combines three drugs over a 25-week period of time. If you believe this could be the right method of treatment for your dog, speak with your veterinarian to get more details about this type of chemotherapy.

A least expensive option would be an approximately $30 charge per injection, Intile said, with costs rising into the thousands for more comprehensive treatments that require a duration of many months and/or more frequent injections. When describing treatment plans to pet parents, “we never say ‘this is the only way to do it,’” she said. “We always come up with options based on their budget, lifestyle and how often they can come in.”

Barber and Intile said that pet insurance should cover some of the costs of chemotherapy, but it depends on the company and the policy. “For some dogs that are particularly prone to cancer, insurance companies may require a specific cancer rider,” Barber said.

A rider provides an insurance policy holder with additional coverage for a specific illness or situation. Insurance companies typically offer these policy options at an additional cost, which can vary widely.

What Can I Expect During My Dog’s Chemotherapy Treatment?

How chemotherapy is administered depends on the drug given. Intile said most treatments are administered by injection and last just a few seconds (similarly to a vaccination) to a few minutes. Some intravenous drug infusions can take all day but are rarer, she said. Other chemotherapy treatments are given orally, in the office or at home.

Intile allows an hour for a chemotherapy treatment appointment, which includes time for paperwork, bloodwork, an exam and follow-up instructions. These appointments are similar to a typical vet visit, she said, and are designed to minimize stress for both dog and pet parent.

What Are the Side Effects of Chemotherapy in Dogs?

Side effects for dogs are milder and generally last for a shorter period of time than for humans receiving chemotherapy because dogs are given less-aggressive treatment, Intile said. In fact, 75 to 80 percent of dogs have no side effects, she said. When present, typical side effects include loss of appetite, vomiting and diarrhea. 

Less than five percent will suffer those effects more severely and will need to be brought into the vet to receive fluids, she said. “There may be little windows of time to restrict activity, maybe days three to five (after treatment). But we don’t want you to put your dog in a bubble. Our goal is for your pet to have a totally normal lifestyle,” she said.

If symptoms do not resolve in a day or two, call your veterinarian.

What causes side effects is the indiscriminate nature of chemotherapy drugs, which kill both normal and abnormal cells in an “innocent bystander” effect, Barber said. Such indiscriminate destruction can affect your dog’s bone marrow, which produces blood cells. “The most common problem that we see is low white blood cell counts. The white blood cells are the first line of defense against infection,” and a low white blood cell count can put dogs at risk for infections, she said.

Unlike people, dogs typically do not go bald from chemotherapy, although they might lose their whiskers, Intile said. Breeds that have hair that grows constantly, such as Poodles, Yorkshire Terriers, Portuguese Water Dogs, can lose some hair, which might grow back in a different color, she said.

How Often Will My Dog Need Chemotherapy?

Frequency of treatments will depend on the type of cancer, the dog’s overall health, the specific drug and family wishes. Most treatments are given in intervals ranging from once a week to once every three weeks, Barber said. That frequency can last a couple of months, followed by every four to six weeks.

The duration of the treatment is also dependent on the type of cancer and can last from a few months to a few years.

“For lymphoma, most standard chemotherapy protocols last between 16 and 24 weeks. However, unless the client wishes to stop, this often is not the end of treatment. Once the initial protocol is completed and the animal is in complete remission (no cancer detected), we give the animals a rest from treatment and wait until we see that the cancer is back. We then start chemotherapy again,” Barber said.

For other types of chemotherapy, particularly when a malignant tumor has been removed and prevention or delay of a reappearance is the goal, a typical course of chemotherapy lasts about three months, she said.

Is it Safe to be Exposed to my Dog’s Chemotherapy Drugs?

The drugs remain active in your dog’s waste for the first few days after treatment, so pet parents are advised to be cautious and to wear gloves when cleaning up after their pet. Intile said her practice provides pet owners with chemo-proof gloves to wear if administering oral drugs and advises them to always wash their hands after administering the drugs and cleaning up, even if wearing gloves.

Women who are pregnant or breastfeeding and those with weakened immune systems, such as the elderly, should be particularly careful around their pet’s waste, she said. However, you do not have to worry about your other pets sharing water bowls, food dishes or utensils with your sick dog, she added.

When storing chemotherapy drugs in your fridge, be sure to keep them in a container within a container away from your own medications. If you do accidentally ingest any of your dog’s medication, call your doctor, not your vet, who by law cannot dispense medical advice to people.

Are There Alternative Treatments for Dogs with Cancer?

Adding to your vet’s cancer arsenal of surgery, radiation and chemotherapy is another option: immunotherapy. This is a type of vaccine that is used to stimulate your dog’s own immune system to attack the cancer. “Right now the main focus for that is in dogs with melanoma (and osteo sarcoma),” Intile said.

Some of the larger veterinary university research hospitals are also using bone marrow transplants to treat some cancers, Intile said. To be sure you and your pet have access to the latest treatments and possible clinical trials, consider bringing your dog to a facility that specializes in veterinary oncology.

Image: Syda Productions via Shutterstock 

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