Necrotizing encephalitis in Yorkshire terriers

Abstract

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.

The Central Nervous System

“…Mononuclear cells may take on changes that are nonspecifi c Necrotizing encephalitis in small breed dogs (Figs. 14-17 and 14-18A-D)-Pugs, Maltese, Shih Tzus, French Bulldogs, and Yorkshire Terriers-is reported to demonstrate multifocal to massive necrosis and nonsuppurative infl ammation of the cerebrum and meninges that is fatal or leads to euthanasia (Uchida et al, 1999;Stalis et al, 1995;Timmann et al, 2007;Tipold et al, 1993). These dogs are usually less than 4 years of age and present frequently with seizures, depression, and ataxia; they do not respond signifi cantly to glucocorticoids.…”

“…Bacteria are not observed or cultured and improvement is often seen within 72 hours following glucocorticoid administration; longterm prognosis is good. One report investigated the immunologic response in these cases fi nding IgG and IgA synthesis intrathecally and suggested the humoral response is primary, rather than the result of a generalized immune complex disease (Tipold et al, 1995). In another more recent paper evaluated clinical fi ndings and prognosis in a series of 12 cases of aseptic suppurative meningitis in juvenile Boxers of which 10 of the dogs exhibited the acute form of the disease and had more than 100 nucleated cells/μl with neutrophils ranging from 72% to 100%.…”

Necrotizing Meningoencephalitis Associated with Cortical Hippocampal Hamartia in a Pekingese Dog

“…A distinctive clinical and pathologic form of necrotizing encephalitis has also been described in Yorkshire Terriers. 6,9,12 The architecture and cytologic abnormalities of the right hippocampus were consistent with a dysplasia restricted to the hippocampal area. The lesion might be due to defective neuronal migration and differentiation during gestation.…”

“…Further observations of a similar disease in Maltese, 10 Shih Tzu, 10 and Chihuahua dogs 12 indicate that this entity may be more widespread among dogs of small size, in particular toy breeds. A distinctive clinical and pathologic form of necrotizing encephalitis has also been described in Yorkshire Terriers.…”

Perspectives on Meningoencephalomyelitis of Unknown Origin

“…3,78,84 Immunohistochemistry studies of lesions in a small cohort of dogs with NME suggest that IFN-g plays a major role in NME. 88 Necrotizing leukoencephalitis NLE has been described in Yorkshire terriers [89][90][91][92][93][94] and French Bulldogs 95,96 with differing clinical and topographic features. Clinically most dogs with NLE have presented with visual loss, seizures, and central vestibular signs reflecting forebrain and brainstem involvement.…”