Radiation Therapy in Dogs and Cats

Hearing your beloved pet has cancer can be scary and there are many different types of treatments. One option for your pet may be radiation oncology. Below you’ll find some of the questions we regularly receive regarding veterinary radiation oncology and your pet.  

How Soon Should My Pet See a Specialist?

If your pet has been diagnosed with cancer, your family veterinarian may refer you to a veterinary radiation oncology specialist. Because tumors grow at varying rates with some doubling in size quickly, it is important to schedule an appointment as soon as possible to discuss your pet’s treatment options and begin therapy.  

What Happens During the First Consultation?

If we have not already received records or test results, including bloodwork, pathology reports, and medical imaging studies, from your family veterinarian, bring them with you to the first appointment. Our radiation oncology team will review your pet’s medical history and examine your pet. They will discuss your pet’s condition, prognosis, and treatment options, and answer any questions you may have. That information will be provided to you and your family veterinarian. Therapy can begin at that first appointment, which can last up to 2.5 hours.  

What is Radiation Therapy and How Does it Work?

Radiation therapy (RT) works by damaging cell DNA, both in the tumor and normal tissue, and killing cells when they divide (except lymphocytes). Depending on the treatment plan for your pet, we administer a full course of RT or palliative RT using radiation therapy beams including X-rays or electrons.  

Full-Course Radiation Therapy

Full-course radiation therapy is used for long-term tumor control and is often combined with surgery and/or chemotherapy. The goal of full-course RT is to maximize tumor cell kill and tumor control, which does increase the likelihood of side effects. Treatment is typically daily, Monday-Friday, over three to four weeks with 16-19 treatments given. Treatments can take up to 1.5 hours. 

Possible early (within a few weeks) side effects from treatment include moist or peeling skin, hair loss, oral ulcers, conjunctivitis, tracheitis, esophagitis, colitis, and urethritis. These side effects are usually temporary and heal within two to four weeks after RT is completed. Possible late or long-term (months or years) side effects include brain, bone, and muscle tissue scars, dry eye, cataracts, or blindness.  

Palliative Radiation Therapy

Palliative radiation therapy is designed to improve or maintain the quality of your pet’s life. Typically, your pet will receive a total of four to six treatments over a three to six-week period. For osteosarcoma, three treatments are given on the initial day, day seven, and day 21. Each treatment can last up to 1.5 hours. Because fewer treatments with larger doses are given for palliative RT, there are generally minimal acute (early) side effects but greater late (after one year) side effects.  

How Should I Prepare My Pet for Their Radiation Therapy?

Your pet should fast for at least 10 hours before each therapy session. Pets may be given water and any previously prescribed medications. During each session, your pet will undergo anesthesia to ensure they remain still for their RT treatment. When the treatment is complete, they are awake within minutes. We will monitor them closely during and after treatment before they are returned to you. 

Throughout your pet’s oncology treatments, we will work closely with your veterinarian to ensure your pet is receiving the best care possible.