Equine Radiation Oncology

Hours & Appointment Scheduling

Office hours: Monday to Friday, 8am to 5pm

For an appointment: 614-292-6661, ext. 2

Emergencies: 614-292-6661
A veterinarian is available for emergencies 24 hours a day, 7 days a week.

External Beam Radiation Therapy in Horses

Equine tumors commonly remain localized for prolonged periods before spreading but can cause serious problems locally. There is a need to develop successful methods of preventing recurrence and prolonging a good quality of life. External beam radiation is a cutting-edge therapy for equine tumors, particularly of the extremities (head and limbs) and skin. 

Treatment decisions always need to be made with full involvement of referring veterinarians, owners, and with considerations for the quality of life, possibility of success, and economics. There are many ways of treating equine tumors with surgical excision, local chemotherapy, cryotherapy, and laser assisted excision being the most common, but recurrence remains a common problem. Systemic chemotherapy in horses is relatively rare due to the expense associated with many medications. At the Ohio State Veterinary Medical Center's Galbreath Equine Center, our team of equine specialists partner with our internal radiation oncology specialists and, in periocular tumor cases, with our internal ophthalmology specialists - all of whom are dedicated to creating the best treatment plan for each horse. The addition of our 128-slice computed tomography (CT) machine further enhances the success of both surgery and radiation therapy, as it allows accurate identification of the structures invovled in the tumor and delineates the radiation field. 

Horses with tumors of the head range in age but often occur in older patients. A variety of tumors occur in the head of horses including squamous cell carcinomas, ameloblastomas, fibrosarcomas, osteosarcomas, adenocarcinomas, and ossifying fibromas. Tumors can occur in sinuses, nasal passage, maxilla or mandible. Surgical excision is the current standard treatment at most referral surgical centers, but tumors frequently recur as complete excision is difficult. For this reason, external beam radiation therapy has been used in combination with surgical excision at the Galbreath Equine Center for the last two decades. The protocols used are tailored to each individual horse, taking into consideration the tumor type and behavior, the economics, and expected results. Palliative and definitive radiation protocols can be designed. In order to receive external beam radiation, the horses must undergo a short (average 15-20 minute) general anesthetic.  A young horse with a large fibrosarcoma in the rostral maxilla and an aged horse with an osteosarcoma encompassing the entire right nasal passage, are just two examples of horses who have received post-operative radiation therapy successfully with no tumor recurrence. Both horses returned to normal athleticism. The success rate has been very promising at preventing or delaying recurrence and prolonging a good quality of life. Importantly, the treatments have been accomplished easily and the horses have an excellent quality of life during treatment. Side effects have been limited to white hair in the radiation field and mild, short-lived mucositis when mucocutaneous junctions are in the radiation field. No systemic illness, inappetence, or depression have been noted. 

Horses with skin tumors can be frustrating to patients as these tumors are very slow to metastasize but can be locally very irritating, cosmetically unsightly, and interfere with funciton. The most common skin tumors are melanomas, sarcoids, and squamous cell carcinomas. Sarcoids have been plaguing veterinarians with their tendency to recur for years and recently, these have been given the option of surgical debunking followed by external beam radiation. Sarcoids in difficult places such as the periocular region, are excellent candidates for radiation therapy. It has been established that sarcoids respond well to radiation as brachytherapy has reportedly been very successful in preventing recurrence. Brachytherapy is the implantation of radioactive beads or ribbons into the tumor. This has some drawbacks, however, as the horses are then radioactive for the duration of therapy and must be housed and treated in special circumstances that are laborious and expensive. 

External beam radiation can be done on an outpatient basis, as the horses are not radioactive at any time. The ease of administration and the lack of significant side effects are amongst the benefits of external beam radiation therapy. Data is being accumulated on the long-term response of sarcoids to external beam radiation therapy, but early results are promising and it has been used successfully in sarcoids that have failed to respond to multiple other therapies. 

At the Galbreath Equine Center, external beam radiation is a cutting-edge, adjunctive therapy being utilized to prolong and improve the quality of life in our equine patients. Questions regarding the use of radiation for equine oncology patients can be directed to Dr. Eric Green, Dr. Margaret Mudge or Dr. Dah-Renn Fu (see contact information below). The clinicians at the Ohio State Veterinary Medical Center and Galbreath Equine Center are dedicated to improving the treatment options available and the methods employed to improve successful outcomes for our equine patients.  

Clinical Trials

The Equine Radiation Oncology service is often recruiting patients for related studies for which your animal may be eligible. If you have any questions regarding your animal's eligibility, please contact the Blue Buffalo Clinical Trials Office (cvm-clinicaltrials@osu.edu). 

For a listing of current trials please click here.