Necrotizing meningoencephalitis

Necrotizing meningoencephalitis (NME) is a fatal inflammatory central nervous system (CNS) disorder, where an extensive cerebral necrosis is associated with a multifocal, non-suppurative meningoencephalitis of the neuro cortex. It was originally identified and recorded in the 1960’s in pure breed pugs, with which this disease is nowadays mostly associated with, occurring essentially in small breed dogs ranging from six months to seven years of age. It causes intense necrotizing inflammatory lesions in the brain stem and Cerebellum. The etiopathology is still unclear. The pathogen that triggers the disease and contributes to its development has not yet been identified. It is presumed to have a multifactorial, heritable, autoimmune etiology. The process is rapidly progressive, culminating in status epilepticus and ending fatally for the dog. Necrotizing meningoencephalitis (NME) is a fatal inflammatory central nervous system (CNS) disorder, where an extensive cerebral necrosis is associated with a multifocal, non-suppurative meningoencephalitis of the neuro cortex. It was originally identified and recorded in the 1960’s in pure breed pugs, with which this disease is nowadays mostly associated with, occurring essentially in small breed dogs ranging from six months to seven years of age. It causes intense necrotizing inflammatory lesions in the brain stem and Cerebellum. The etiopathology is still unclear. The pathogen that triggers the disease and contributes to its development has not yet been identified. It is presumed to have a multifactorial, heritable, autoimmune etiology. The process is rapidly progressive, culminating in status epilepticus and ending fatally for the dog. Although the pattern of inflammation is similar to other neuropathological conditions, resembling CNS inflammatory diseases which produces lesions alike to those that occur in NME, a definitive diagnosis can be made solely based on by histopathological examination through a necropsy. First signs of this immune dysregulation can show through lethargy and the reluctance to walk. Behavioral changes and an abnormal mentation might occurf. After a short amount of time vestibulo-cerebellar symptoms will rapidly progress, leaving the animal in a state of depressed consciousness having seizures, amaurosis and ataxia. Despite seizures being a promoting factor of necrosis in primary inflammation diseases, it's not proven that the necrosis is extending to the white matter due to these convulsions. An antemortem diagnosis is often intricate considering the similarities of general neuro diagnostic profiles. To achieve a presumptive diagnosis on the live animal a multimodal approach is needed. Including the magnetic resonance imaging (MRI), computer tomography (CT), cerebrospinal liquid (CFS) analysis and immunological test. Since only the CNS is affected by the pathology, there won’t be any characteristic changes in organ systems other than the nervous system. Despite clinical examination methods, the specific diagnosis of NME depends on a postmortem, histopathological examination of the brain biopsy tissue or a necropsy. When examining the transversal sections, the non-suppurative (lymphoplasmacytic and histiocytic) inflammation of both the meninges and encephalitis have characteristic histopathologic changes of necrotizing nature in the corona radiata (white matter), the thalamus and the cerebrocortical area. The meninges itself is focally thickened by dense aggregations of lymphocytes, plasma cells and macrophages infiltrating due to the reinforced immune answer (perivascular cuffing). Several multifocal encephalic lesions in corona radiata are erasing the border in the cerebral hemispheres between white and grey matter, exposing an asymmetrical ventricular enlargement. These lesions are selective with a predilection for the cerebral hemisphere.