Treatment of MRI-Diagnosed Trigeminal Peripheral Nerve Sheath Tumors by Stereotactic Radiotherapy in Dogs.

BACKGROUND: Stereotactic radiotherapy (SRT) is an emerging technique for treating tumors in animals. OBJECTIVES: To assess the outcome of dogs with suspected intracranial trigeminal nerve peripheral nerve sheath tumors (PNST) treated with SRT. ANIMALS: Eight dogs with presumptive PNST. METHODS: This was a retrospective study of dogs identified by searching UC Davis Veterinary Medical Teaching Hospital medical records for dogs treated with SRT for a presumed PNST. Presumptive diagnosis was based on magnetic resonance imaging. SRT was delivered in 3 dose fractions of 8 Gray (Gy) on consecutive days or every other day to a total dose of 24 Gy. RESULTS: Median disease-specific survival was 745 days (range: 99-1375 days, n = 6). No signs of acute adverse effects of radiation treatment were recorded. Late radiation effects versus tumor progression could not be confirmed histopathologically because of few animals undergoing necropsy. CONCLUSIONS AND CLINICAL IMPORTANCE: This study provides preliminary evidence that dogs with PNST benefit from SRT in terms of long-term survival. The treatment appears to be well tolerated and requires fewer anesthetic events for animals compared to full-course radiation.