Treatment Outcomes of Canine Orbital Meningiomas in Seven Cases

Although intracranial and spinal cord meningioma prognoses have been reported, few studies have evaluated the outcomes and prognoses of orbital and optic nerve meningiomas in dogs. We aimed to evaluate the outcomes of canine orbital meningiomas. The seven dogs included were cytologically or histopathologically diagnosed with meningiomas. Four underwent first-line surgery; three received postoperative radiation therapy. The remaining three underwent first-line radiation therapy; however, 372 days after radiation therapy, one dog underwent surgery as the lesion progressed in size. Five dogs underwent surgical resection, had incomplete resections, and died during the observation period, with a median survival time of 943 days (range 668-1083 days). The two surviving dogs were followed up for 119 and 1083 days. Local recurrence was detected in three of the five dogs at 478, 660, and 814 days. The median progression-free survival was 569 days (range 262-814 days). Although keratoconjunctivitis (grade 2) was observed in one dog that underwent eye-sparing radiation therapy, no serious side effects were observed in the other dogs. Our results suggest that surgery and radiation therapy may play an important role in the treatment of orbital meningiomas and may offer longer survival than that of brain or spinal cord meningiomas.