Necrotizing encephalitis in Yorkshire terriers

During the past six years these authors have observed a distinctive multifocal non‐suppurative necrotizing encephalitis in Yorkshire terriers. Histopathological findings were different from those in canine encephalitides of known and unknown causes. Clinically, the Yorkshire terriers presented primarily brain stem signs or evidence of cerebral involvement, including seizures. The course of the disease was mostly chronic and progressive. Protozoal, bacterial and mycotic organisms were not found on histopathological examinations. The morphology of the lesions was strongly suggestive of a viral aetiology. Immunocytochemistry as well as in situ hybridisation failed to provide evidence for canine distemper virus infection. Likewise, canine herpesvirus was not detected by immunocytochemistry. Other known canine encephalitides could be excluded on clinical and morphological grounds; however, certain similarities may exist to pug dog encephalitis.