猪捷申病毒性脑脊髓炎，血管周围单核细胞套状浸润

Photomicrograph of marked perivascular mononuclear cuffing. Rarely, there are scattered eosinophils within the infiltrate. This is frequently observed in affected animals that are markedly dehydrated and cannot reach water outlets (secondary salt toxicosis). This lesion in some cases is almost indistinguishable from chronic salt toxicosis, so other ancillary molecular methods are needed for proper diagnosis.