A new rat mutant with defective overhairs and spongy degeneration of the central nervous system: clinical and pathologic studies.

A new spontaneous autosomal recessive mutation with a nervous disorder and a hair anomaly occurred in a colony of Sprague Dawley rats. The animals developed a generalized body tremor at about 15 days of age, and with increasing age a progressive flaccid paresis occurred. Light microscopy revealed spongy changes in the central nervous system. The mutant was designated zitter rat (zi).