Radiation Therapy Shrinks Dog’s Brain Tumor, Extending Life by Years

Three years ago, Scramble, a 9-year-old Jack Russel terrier, began developing behavioral changes, including aggression and disorientation. He experienced tremors while sleeping, and his owners observed a seizure shortly thereafter. He was brought to the Neurology/Neurosurgery Service at the UC Davis William R. Pritchard Veterinary Medical Teaching Hospital (VMTH) for a thorough examination.  

An MRI performed on Scramble revealed a large brain tumor, most likely a meningioma, had developed in his right cerebral hemisphere. While the tumor was inoperable, the neurologists believed it could be managed with the help of the VMTH’s oncology team.

Dr. Michael Kent, chief of the Radiation Oncology Service, recommended a course of stereotactic radiotherapy (SRT) in an attempt to shrink the tumor. SRT is a type of radiation therapy that utilizes CT scanning and MRI guidance for precise delivery of a series of high doses of radiation directly into a targeted tissue area while minimizing injury to surrounding tissues.

Radiation therapy is conducted on the VMTH’s state-of-the-art linear accelerator, one of the most advanced accelerators at any veterinary hospital in the world. During treatment, the linear accelerator rotates around the patient, delivering radiation through multiple arcs. The machine’s built-in CT scanner allows the treatment to be as precise as less than 1 millimeter from the edge of the tumor.

Scramble received three sessions of SRT in a three-day period. The procedure went well, and he recovered without complications. Following treatment, Scramble showed a significant improvement in his neurologic status.

However, approximately 18 months after treatment, Scramble began to show early signs of recurrence of his initial behavioral issues. His owners noticed an increase in trembling, particularly in his hind legs. He also had his first seizure since the SRT treatment months before.

Another MRI revealed that while Scramble’s tumor was smaller than when initially diagnosed (confirming that a reduction in tumor size had been achieved with SRT), it was likely growing again. It was elected to treat Scramble with another round of SRT treatments, which once again significantly improved his neurologic status.

“We’re thrilled with the outcome,” said Scramble’s owners. “The specialty care Scramble has received from the Neurology/Neurosurgery and Radiation Oncology Services at the VMTH has been superb.”

Now, two years after that second round of SRT, 12-year-old Scramble continues to do well.

“Stereotactic radiotherapy can be a really good option for many dogs experiencing brain tumors,” said Dr. Kent. “We’re so thrilled to see Scramble doing well more than three years after his initial treatment. One of the most rewarding aspects of my job is keeping families together for as long as possible with a really good quality of life.”

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