By Kristine McComis, May 2009
Debbie Klein’s 7-and-a-half-year-old Sheltie and agility show dog, Lorelei, suddenly began having seizures. Lorelei had been to The Ohio State University Veterinary Medical Center in the past, so Klein called to make an appointment with our neurology service to pursue testing. A week after the episode, an MRI revealed a mass in Lorelei’s olfactory lobe. The imaging confirmed features consistent with a meningioma, the most common brain tumor for dogs and cats. In Lorelei’s case, it was located deep to the frontal sinus. Surgery is an option for these types of tumors, but canine meningiomas tend to microscopically invade adjacent brain tissue, so there is a risk of leaving residual tumor. Chemotherapy is an option, but is usually not as effective as other treatments. Radiation therapy alone (or combined with surgery) is usually the best treatment option.
“The doctors discussed all of the possible options with me,” Klein said. “I had five dogs at the time, and given the nature of the home environment and other risk factors, we decided that the best course of treatment for Lorelei was radiation therapy with no surgery.”
Lorelei was started on Phenobarbital, which successfully controlled her seizures. After a few weeks, Dr. Eric Green, clinical professor of Radiation Oncology, designed a treatment plan using state-of-the-art 3D radiotherapy planning software. Lorelei underwent radiation treatments daily for four weeks. Her tumor was treated using two parallel-opposed fields of radiation, aiming a beam between her eyes from above the top of her head and from underneath her jaw. This spared her eyes from receiving any significant dose of radiation.
“This was a very aggressive treatment, as Lorelei had to undergo a total of 20 brief anesthesias as well, but she tolerated everything beautifully,” Dr. Green said. Because of the two and a half hour drive from Columbus to Cleveland, Lorelei stayed in the hospital for the majority of her treatment, although she did go home one weekend for a visit. After her four-week course of radiation, Lorelei went home without any radiation side effects. She returned three months later for a re-evaluation by our neurology service and was still seizure free. She then came back for a repeat MRI nine months later; the tumor had shrunk dramatically. We reduced the dosage of her anti-seizure medication and she began performing in agility demonstrations again.
“The usual expectation after treating a meningioma is control of clinical signs and shrinkage of mass for at least one year,” Dr. Green said. “Tumors over the cerebrum can do very well with radiation treatment.” However, Lorelei was thriving nearly four and a half years after her radiation treatment, an amazing result, to which Dr. Green remarked, “It works!”
The brain radiation protocol is usually well-tolerated with a few radiation side effects. As long as a patient can handle a brief (usually 10 minutes or less) daily general anesthesia, radiation therapy should be considered for the long term management of brain tumors. “Her quality of life did not go downhill,” Klein said.