A comparative pathological study on canine necrotizing meningoencephalitis and granulomatous meningoencephalomyelitis

Area of Science:

• Veterinary Pathology
• Canine Neurology
• Immunohistochemistry

Background:

• Canine necrotizing meningoencephalitis (NME) and granulomatous meningoencephalomyelitis (GME) are inflammatory central nervous system diseases in dogs.
• Distinguishing between NME and GME is crucial for understanding their distinct pathological processes and potential treatments.

Purpose of the Study:

• To compare the pathological and immunohistochemical features of canine necrotizing meningoencephalitis (NME) and granulomatous meningoencephalomyelitis (GME).
• To identify key differences in lesion distribution, cellular infiltration, and macrophage characteristics between NME and GME.

Main Methods:

• Gross pathological examination of canine brains affected by NME and GME.
• Histopathological analysis of lesion distribution and inflammatory cell types.
• Immunohistochemical staining for specific cell markers (RCA-1, lysozyme, MAC387, CD3).

Main Results:

• NME lesions predominantly affected the cerebral cortex with necrosis, while GME showed milder gross changes and granuloma formation, mainly in white matter.
• GME exhibited more extensive infiltration of epithelioid macrophages and MAC387-positive cells compared to NME.
• While both disorders had abundant RCA-1-reactive cells, NME had fewer lysozyme-positive cells than GME. CD3-positive lymphocytes were slightly more numerous in GME.

Conclusions:

• Morphological and immunohistochemical differences, particularly in macrophage infiltration and transformation, highlight distinct pathogeneses for canine NME and GME.
• These findings aid in differentiating NME from GME and provide insights into their underlying disease mechanisms.