MRI findings in a case of canine tick born meningoencephalomyelitis

Tick borne encephalitis virus (TBE) is an endemic infectious agent in northeastern Switzerland causing mainly meningoencephalomyelitis in dogs. We report a canine case of tick born meningoencephalomyelitis resulting in flaccid tetraplegia and, subsequently, fatal respiratory failure. Magnetic resonance imaging (MRI) demonstrated intra-axial bilateral, symmetric, and hyperintense lesions in T2-weighted and Fluid Attenuated Inversion Recovery (FLAIR) sequences affecting thalamus, basal nuclei, cerebral white matter and ventral horns of the caudal cervical spine. These radiological findings overlap those described during flavivirus encephalitis affecting human beings. These lesions in MRI and diffusion weighted images correlated with areas of vasogenic edema detected histopathologically. In endemic regions, clinicians should be aware that bilateral, symmetrical hyperintense thalamic lesions in T2WI can be suggestive of flavivirus infection in dogs with encephalitis.