Finding out your dog has cancer can feel devastating. Thankfully, you have options. Advances in the field of veterinary oncology mean that multiple treatment options are available. Depending on many factors, these can be options to help extend and improve their life. Among these treatment options is radiation therapy for dogs.
Radiation therapy can be used on its own. It can also be used with other treatments to shrink some types of tumors, slow disease progression, and reduce pain and inflammation. Understanding how the treatment works can help you make informed decisions that support your pet during this challenging time.
Key Points
What Is Radiation Therapy for Dogs?
Radiation therapy for dogs uses machine-generated energy waves or particles to treat diseases, especially cancer. The targeted doses of ionizing radiation, which are significantly higher than those required for X-ray imaging, damage the DNA of rapidly growing and dividing cancer cells while minimizing damage to surrounding healthy tissue. This can help to kill, shrink, or slow tumor growth, and reduce tumor-related pain and discomfort.
What Can Radiation Therapy Treat in Dogs?
Dr. Celina Morimoto is a veterinary radiation oncologist and assistant clinical professor at Cummings School of Veterinary Medicine at Tufts University who uses radiation therapy to treat dogs.
“We often treat nasal tumors, brain tumors, cancers in the mouth, tumors near or in the heart, and some cancers in the abdomen,” Dr. Morimoto says. “Radiation may also be used when a tumor is too large for surgery to remove it, or if the goal is to simply use radiation to improve pain control, like for painful cancers in the bone or the mouth.”
Radiation might be combined with chemotherapy or immunotherapy to improve tumor control or stimulate systemic immune responses. “For example, half-body radiation in combination with chemotherapy has been shown to improve the survival for dogs with lymphoma,” says Dr. Thomas Ber-In Lee, Assistant Professor in Radiation Oncology at Penn Vet Cancer Center, University of Pennsylvania.
Dr. Lee explains that by combining radiation with immunotherapy, veterinary oncologists aim to create and enhance what’s known as the abscopal effect. This is where the combination of both treatments induces a systemic immune response, which can lead to the regression of other tumors elsewhere in the body — ones that weren’t specifically targeted.
Low-dose radiation can also treat non-cancerous diseases and chronic inflammatory-related diseases, such as osteoarthritis and chronic urinary tract inflammation. Dr. Lee explains that modulating the local immune response in this way can slow down inflammation and reduce discomfort, pain, and certain clinical symptoms.
Types of Radiation Therapy for Dogs
A spectrum of care is available for dogs undergoing radiation therapy. Your veterinary oncologist will tailor and deliver it with different goals in mind, depending on the type, location, and stage of the disease.
Definitive-Intent Radiation Therapy
“The goal of definitive-intent protocols is to try to maximize local tumor control in hopes of achieving the longest survival,” Dr. Morimoto says. Veterinary oncologists will often choose this highly targeted and concentrated dose of radiation when a dog’s tumors are difficult to remove surgically or when cancer cells remain after surgery.
Palliative-Intent Radiation Therapy
“Palliative-intent may be recommended for certain types of tumors that have a high risk of metastasis (spread), for patients who already have metastasis, or if patients have other important health issues that are likely to affect their long-term survival,” Dr. Morimoto says. “The goal of palliative-intent radiation is to improve patient comfort and minimize the risk of side effects.”
Rather than attempting to cure or significantly shrink the tumor, this approach focuses on reducing pain, bleeding, inflammation, or tumor pressure. Although it may not significantly extend survival, it can play a crucial role in enhancing your dog’s quality of life.
While protocols vary, the number of sessions and total dose are typically lower than those required for definitive-intent protocols. Dr. Lee explains it’s commonly used for dogs with osteosarcoma, a painful bone cancer. “Sometimes the patient is not a good candidate for amputation, or they already have metastasis, and the long-term prognosis is not great,” he says. “Over 90% of patients will respond to palliative radiation, with the pain reducing within about a median of two weeks.”
How Is Radiation Therapy for Dogs Administered?
They’ll typically perform a CT scan before commencing radiation therapy to allow them to formulate a plan that effectively targets the tumor or reduces symptoms.
Regardless of the protocol, your dog will be placed under general anesthesia during each session to ensure they remain still. “The positive side is that anesthesia for radiation treatments is much shorter (commonly 15–30 minutes) and lighter compared to surgery, a CT scan, or an MRI,” Dr. Morimoto says.
If you live near the hospital, in most circumstances, patients can receive treatment on an outpatient basis. At other times, they may remain in the hospital for their treatment or go home on weekends.
Definitive-Intent Protocols
Veterinary oncologists typically deliver high doses of radiation in two ways, depending on the type of tumor and its location.
The first is conventionally fractionated radiation therapy, which Dr. Morimoto says involves 10 to 20 daily treatments, Monday through Friday.
The second is stereotactic radiation therapy, and it involves administering much higher doses over fewer days. “This is 3 to 5 treatments that are usually completed within less than two weeks,” she says. While this can also spare the surrounding normal tissue, Dr. Morimoto cautions that it may not always be the best option for all cancers or all tumor locations.
Palliative-Intent Protocols
While it can vary, Dr. Morimoto says that the total number of visits for palliative-intent protocols most commonly range from 4 to 6 treatments.
Side Effects of Radiation Therapy for Dogs
Radiation therapy side effects are usually mild to moderate and manageable, although they vary depending on tumor location, treatment intensity, and the protocol used.
“As veterinary radiation oncologists, we don’t like to prescribe something that will significantly compromise your dog’s quality of life—we want to maintain or even improve it,” Dr. Lee says. This is why the sessions aren’t typically as aggressive or frequent as in human medicine.
Side effects are categorized as acute (short-term) and late (long-term). Acute side effects can last for a week or two immediately after treatment and often involve the skin.
“The risk of radiation skin side effects depends on where the tumor is located,” Dr. Morimoto says. “Tumors near the skin are more likely to have some degree of skin side effects, varying from focal hair loss to redness (severe sunburn-like look) in worst-case scenarios.”
She explains that, with modern radiation machines, if your veterinary oncologist is treating a deeper tumor in your dog’s body (i.e., brain tumor), then skin burns aren’t commonly seen.
Dr. Lee explains that systemic side effects, such as nausea or widespread illness, are rare. “Sometimes your dog may have some GI upset, like diarrhea, but this would be because of the stress in the hospital,” he says. “It’s not directly related to the radiation.”
Late side effects are rare, but they can appear months or years after treatment. These can include permanent hair color changes, scar tissue formation, or bone or nerve damage.
Dr. Morimoto explains that the radiation beam doesn’t cause pain during treatment, and you don’t need to worry about your dog becoming radioactive. “Receiving external beam radiation therapy from a linear accelerator means that we are giving high-energy X-rays,” she says. “The high-energy x-rays are in and out immediately during the radiation session.”
Deciding if Radiation Therapy Right for Your Dog
While radiation therapy can be an effective tool in managing cancer or inflammatory pain in dogs, it’s not suitable for every pet or owner.
Your dog’s cancer type and stage, their overall health, and how well they handle veterinary visits factor into whether radiation is appropriate. There are also practical considerations, such as time and travel logistics. Additionally, the specialized equipment and team of trained professionals required to administer radiation therapy mean it can be a costly process.
The cost of radiation therapy for dogs varies depending on the complexity of the case, the protocol chosen, the number of doses required, and whether other treatments are also being administered. Palliative-intent protocols designed to relieve symptoms may cost from $1,000 to $3,000. More advanced definitive-intent protocols, such as stereotactic radiation therapy (SRT) designed to target tumors with greater precision, can cost $8,000 to $10,000 or more.
Many comprehensive pet insurance plans cover radiation therapy. They may reimburse from 50% to 90% of treatment costs, as long as the cancer isn’t classified as a pre-existing condition. If you have any doubts, check with your insurance provider before beginning treatment.
It’s also important to recognize that a cure isn’t the goal for veterinary oncologists with this type of treatment. “That would result in us causing a lot more side effects to the pets we treat, which would directly affect their quality of life,” Dr. Morimoto says. Instead, the focus is on improving or maintaining your dog’s quality of life, while managing tumor growth or symptoms.
Dr. Lee recommends scheduling a consultation with a board-certified radiation veterinary oncologist to determine if radiation therapy is right for your dog. They can help you understand all available options, expected outcomes, and whether the treatment aligns with your goals for your pet.
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