Radiation Therapy

Radiation therapy is a common form of treatment for many types of cancer in pets. It uses a beam of energy focused on the region of the tumor to gradually eliminate cancer cells by damaging their DNA.

The main goal of radiation therapy is to achieve remission, slow cancer growth, or prevent local recurrence of many types of cancer. Radiation treatment is often used in conjunction with surgery and/or chemotherapy.

PetCure Oncology and Veterinary Cancer Group are Thrive Pet Healthcare partners that help pets fight cancer with advanced technology, veterinary oncology specialists, and true compassion.

Learn more about PetCure Oncology nationwide radiation therapy by visiting the PetCure Oncology website or calling 1-833-PET-HERO. For Southern California, visit the Veterinary Cancer Group website to learn more about radiation centers in this region.

Thanks to modern veterinary medicine, there are several types of radiation therapy now available to help pets with cancer. The type of radiation used will be decided based on multiple factors, including:

Tumor location
Tumor size
Whether the cancer has spread (metastasized)
If radiation is being used in conjunction with other cancer treatments
The goal of treatment such as remission, slowed growth, or symptom management
The pet owner's personal situation and preferences

After the radiation oncologist has assessed the pet’s case, collaborating closely with the whole oncology team, they will discuss options with the caregivers and map out a personalized treatment plan. Find Veterinarians Near You

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Different Types of Pet Radiation Treatment

Stereotactic Radiation Therapy (SRT)

Stereotactic radiation therapy, also known as SRT, uses focused radiation beams to target tumors with unprecedented precision. Because of this accuracy, normal surrounding tissue is mostly spared, minimizing damage to healthy areas and decreasing potential side effects.

SRT is used to treat tumors that would otherwise be considered inoperable or untreatable through traditional radiation therapy. It can target the brain, nasal, prostate tumors, mast cell tumors, osteosarcomas, and tumors located near vital organs.

Stereotactic radiation therapy offers the shortest treatment schedule. The entire radiation dose can be delivered in 1 to 3 sessions lasting less than 15 minutes each and is usually completed within just one week. This greatly reduces the number of times a patient must undergo anesthesia, while also providing added efficiency and convenience for the pet’s caregivers.  

Image-Guided Radiation Therapy (IGRT)

Image-guided radiation therapy (IGRT) is one of the most important innovations in cancer treatment. The slightest body movement, such as breathing, can cause the targeted tumor to move. IGRT allows for precise location mapping, tracking and treatment delivery.

Strontium-90 Plesiotherapy

Strontium–90 Plesiotherapy is used to treat superficial (surface–level) tumors of the skin, including eyelids and ears, many of which are difficult to remove surgically. The dime–sized radioactive probe delivers low energy radiation that only travels about 4mm deep, avoiding any underlying body systems while effectively treating the tumor.

Treatment is usually completed in one or two 5–10–minute sessions, and side effects are rare due to the low penetration level of the radiation. 

Palliative Radiation Therapy

The goal of palliative radiation therapy is not to cure the pet’s disease, but to improve their quality of life by reducing the pain and swelling that accompanies some tumors.  

Treatments are typically given 1–6 times per week over 1–6 weeks. Not all pets benefit from palliative care, but those who do can start to experience improvements within days of the first dose. Benefits often last 2–4 months or longer and can be repeated for most patients when symptoms of the cancer return.  

Definitive Radiation Therapy

When surgery is not performed prior to radiation treatment, it is called definitive radiation therapy. This approach to treatment is typically used when a tumor cannot be surgically removed without great risk or complications for the pet, like those inside the nasal passage, perineum and brain, and some soft tissue sarcomas.

Because the radiation passes through normal tissue surrounding the tumor, multiple small doses of radiation are given to maximize the damage to the abnormal cancerous tissue while minimizing the damage to the surrounding normal tissue.

Definitive radiation treatments are typically given over 5 consecutive days or twice a week for 3-4 weeks.

Conventional Radiation Therapy

Conventionally fractionated radiation therapy (CFRT) uses targeted radiation to shrink or destroy cancers that cannot be safely or completely removed by surgery alone. It can also be utilized in conjunction with, or in place of, chemotherapy, or delivered following surgery if the initial procedure is unable to completely remove cancer. CFRT is typically administered in 15–21 treatment sessions over 3–7 weeks. Pets will need to be anesthetized to ensure they remain still during each session.

Intensity-Modulated Radiation Therapy (IMRT)

Like conventional radiation therapy, IMRT uses multiple doses of small increments of high-energy x-rays to target a tumor, and is also usually given on a daily Monday through Friday schedule over a period of 3 weeks to 1 month. Like SRS and SBRT, IMRT is another complex and precise method of delivering radiation therapy that relies on detailed imaging and computerized three-dimensional treatment planning to obtain the accuracy needed to minimize radiation side effects.

Due to its precision, IMRT spares the surrounding normal tissue and is beneficial for tumors in the nasal cavity or regions where radiosensitive structures need to be avoided. The radiation oncologist determines if IMRT would be more beneficial than conventional radiation therapy or stereotactic radiation therapy.

What to Expect for Your Pet’s Radiation Treatment:

Treatment Planning

Your veterinary radiation oncologist will determine the number of treatments your pet will require based on the form of radiation therapy, type of tumor, and tumor location. A CT scan is often required during the treatment planning phase to help identify and target the tumor most accurately.

Pre-Treatment Testing

Since treatment requires your pet to stay completely still, general anesthesia is required. Blood tests, X–rays (radiographs), and ultrasounds are typically performed prior to CT scanning to ensure your pet does not have metastatic disease and is healthy enough to be placed under anesthesia.

Treatment Administration

Your pet will be placed under general anesthesia to ensure they stay completely still throughout the session, and careful monitoring is performed to minimize associated risk. 

Depending on the type of radiation therapy your pet is receiving, their session can range anywhere between 5–20 minutes long. After every treatment, your pet can return home and experience their normal routines.  

Treatment Series Completion

Once all treatments are finished, your pet will need to attend follow–up visits with their oncologist. These are typically scheduled for two weeks post–treatment and then every three months moving forward or as advised by your pet’s oncology team.  

These visits are very important because the effects of radiation can occur over the following days, weeks, or even months, so it’s important for the oncologist to monitor the recovery process.

Potential Side Effects of Radiation Therapy

As with any type of cancer treatment, certain side effects can occur with radiation therapy, but since this therapy is limited to one region of the body, effects are typically restricted to that area. It is important to discuss any unusual symptoms or behaviors with your oncology team so they can provide remedies and recommendations to keep your pet as comfortable as possible.  

The specialists at PetCure Oncology and Veterinary Cancer Group are experts in their field and take every precaution possible to prevent adverse effects, while giving you and your pet the best chance of a longer, happier future together.