[Pathomorphology of feline dysautonomia (Key-Gaskell syndrome). Histologic, electron microscopic and immunohistologic findings in 4 cats].

The histopathologic, immunohistochemical and electronmicroscopic findings of four dysautonomic cats are presented. The main histopathologic changes were seen in the nervous system, e.g. in sympathetic and parasympathetic ganglia that were similarly affected. Acute cases showed a degeneration of most of the neurons, in one subacute case less neurons and degeneration of some of the remaining neurons were present. Degenerating neurons were swollen or shrunken and had pycnotic, eccentric nuclei. The Nissl substance was lost, the cytoplasma stained eosinophilic and was often vacuolated. Degenerating neurons were also seen in some nuclei of cranial nerves. In sympathetic ganglia numbers of glial cells were increased as shown by immunohistochemical markers (GFAP, S-100). The main ultrastructural changes in sympathetic ganglia were eccentric, crenated nuclei, loss of Nissl substance, loss of ribosomes, distended cisternae and vacuoles filled with floccular material. Circular stacks of parallel smooth-membranes and autophagic vacuoles were also often seen. No normal Golgi fields were seen. These findings closely resemble those already described for feline dysautonomia.