Page 1218 - Veterinary Immunology, 10th Edition

Necrotizing Meningoencephalitis
VetBooks.ir Three somewhat similar inflammatory diseases of the canine central

nervous system are recognized. These are necrotizing

meningoencephalitis (NME), necrotizing leukoencephalitis (NLE),
and granulomatous meningoencephalomyelitis (GME). They each
have distinct lesions, clinical manifestations, and breed
predispositions. They may be immunological in origin. Canine

NME is an inflammatory disease of unknown etiology that has been
described in several toy breeds such as Pugs (young females),
Papillons, Shih Tzu, Maltese Terriers, Pekinese, and Chihuahuas.
The necrotic lesions are multifocal and asymmetrical, restricted to

the gray and white matter in the cerebra, and are accompanied by a
severe meningitis. Macrophages predominate in the lesions, but
both scattered T cells and dendritic cells are present in the lesions,
whereas B cells are restricted to the meninges. Dogs with NME

have autoantibodies to glial fibrillary acidic protein, but the
significance of these is unclear. In at least one case, an affected dog
had a concomitant glomerulonephritis with smooth linear basement
membrane staining for IgG, suggesting the presence of anti–

basement membrane antibodies.
NLE has been reported in Yorkshire Terriers and French
Bulldogs. It is similar to NME but the necrotic foci are found
predominantly in the white matter of the forebrain and brainstem.

These foci are characterized by cavitation, necrosis, demyelination,
and perivascular cuffing. The primary infiltrating cells are T cells.
Some investigators consider NLE to be a variant of NME.
The third form of canine nonsuppurative encephalitis, GME, may

account for a quarter of canine central nervous system diseases.
GME is characterized by the formation of multifocal granulomas
around blood vessels in the cerebellum and brainstem. T cells and
macrophages predominate in the lesions. GME may be

disseminated, focal, or ocular. The prognosis is poor, although
aggressive treatment with corticosteroids may be beneficial. IFN-γ
and IL-17 are elevated in NME and GME. The IL-17 in GME
appears to be produced by macrophages rather than T cells.

Degenerative Myelopathy

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