A shortened whole brain radiation therapy protocol for meningoencephalitis of unknown origin in dogs

Robert Herzig; Katrin Beckmann; Maximilian Körner; Frank Steffen; Carla Rohrer Bley

doi:10.3389/fvets.2023.1132736

A shortened whole brain radiation therapy protocol for meningoencephalitis of unknown origin in dogs

Front Vet Sci. 2023 Mar 20:10:1132736. doi: 10.3389/fvets.2023.1132736. eCollection 2023.

Authors

Robert Herzig¹, Katrin Beckmann¹, Maximilian Körner², Frank Steffen¹, Carla Rohrer Bley²

Affiliations

¹ Division of Neurology, Department for Small Animals, Vetsuisse Faculty, University of Zurich, Zürich, Switzerland.
² Division of Radiation Oncology, Department for Small Animals, Vetsuisse Faculty, University of Zurich, Zürich, Switzerland.

Abstract

Introduction: A variety of treatment options have been described for canine meningoencephalitis of unknown origin (MUO). Few studies focused on radiation therapy as a second line immunomodulating treatment, implicating its effective use. However, a standard radiation therapy protocol is lacking, and further research will help to evaluate the effect of different dose regimens.

Methods: Ten dogs diagnosed with MUO based on MRI and CSF findings were prospectively enrolled. The dogs were treated with a shortened whole brain radiation therapy protocol (5 × 4 Gy) in combination with prednisolone. Neurologic changes were quantified using an established scoring scheme. Follow-up MRI and CSF examination was scheduled three months after radiation therapy. Overall survival and time to progression were calculated. Histopathology of the brain was performed in case of death.

Results: Seven dogs were diagnosed de novo and three had a history of relapsing MUO. Neurological status improved in all 10 dogs during radiation therapy, with 4/10 returning to normal shortly after radiation therapy. Three dogs died within the first three months after radiation therapy. At follow-up MRI lesions completely resolved in two dogs, partially resolved in five dogs, and progressed in one dog. After follow-up MRI, dogs were further treated with prednisolone monotherapy (two dogs) and additional immunosuppressant drugs (five dogs). Overall, four dogs showed disease progression, with a mean time to progression of 691 days (95%CI: 396-987) and mean overall survival for all dogs was 723 days (95%CI: 436-1011) (both medians not reached). Histopathology confirmed MUO in three dogs but was suggestive for oligodendroglioma in one dog. Radiation induced side effects were not seen.

Conclusion: Shortened whole-brain radiation therapy could be an additional treatment option for MUO in conjunction to prednisolone, specifically for cases that require rapid relief of symptoms and with relapsing history.

Keywords: MUE; MUO; brain; canine; encephalitis; inflammation; radiotherapy.

Grants and funding

Albert-Heim-Stiftung provided funding to this study (AHS project number 145).