Spongy degeneration in the central nervous system of domestic animals. Part I: Morphology.

Spongy degeneration or status spongiosus of the central nervous system (CNS) was described in a number of domestic animal species, notably sheep, cattle, pigs and in one goat. The condition was characterized by diffuse or focal vacuolation, or polymicrocavitation of the CNS, particularly the white matter. The vacuolation showed a well defined pattern of distribution following a number of myelinated tracts in CNS white matter, in isolated fibres crossing grey matter in the brain stem, and along grey and white matter borders in the cerebrum and spinal cord. The vacuoles were not altered by a variety of methods of rapid brain fixation, processing and staining. The appearance of the vacuolation repeatedly favouring the same areas in the CNS in a large number of animals studied, its common origin either by hepatocerebral disease or hyperammonaemia, strongly suggests that CNS spongy degeneration of domestic animals is a distinct disease entity.