# Novel Magnetic Resonance Imaging Findings of Bilaterally Symmetrical Lesions in a Dog With Concomitant Granulomatous Meningoencephalitis and Necrotizing Encephalitis

## TL;DR

A dog showed unusual brain lesions seen on MRI, possibly caused by an autoimmune condition, which had not been reported before in canines.

## Contribution

This case report documents previously unreported bilaterally symmetrical canine brain lesions suspected to be secondary to an autoimmune inflammatory etiology.

## Key findings

- MRI identified bilaterally symmetrical T2W/T2-FLAIR hyperintense lesions in the basal nuclei, hypothalamus, midbrain, and occipital lobes.
- Histopathology confirmed granulomatous meningoencephalitis and necrotizing encephalitis.
- Lesions showed restricted diffusion and hemorrhage in the caudate nuclei.

## Abstract

A 3‐year‐old, female neutered Bichon Frise was presented with a 2‐day history of behavioral changes and ataxia. The neurological examination was consistent with diffuse forebrain involvement, with left lateralization. An MRI study identified bilaterally symmetrical T2W/T2 fluid‐attenuated inversion recovery (T2‐FLAIR) hyperintense, T1W hypointense, non‐enhancing lesions involving the basal nuclei, with restricted diffusion and hemorrhage affecting both caudate nuclei. Similar bilaterally symmetrical T2W/T2‐FLAIR hyperintense lesions were noted in the hypothalamus, midbrain, and occipital lobes. Histopathological examination indicated concomitant granulomatous meningoencephalitis and necrotizing encephalitis. This case report documents previously unreported bilaterally symmetrical canine brain lesions suspected to be secondary to an autoimmune inflammatory etiology.