Spontaneous occurrence of spastic paresis in Han-Wistar rats.

The occurrence of spastic paresis and paralysis in rats of the Han: WIST strain is described. The results of this study indicate that this neural disorder starts with progressive development at the age of about 4-5 weeks independent of the sex. At this time the affected animals are significantly smaller than the normal ones. The disease has been found to be due to an autosomal recessive gene. Electromyographic studies showed spontaneous discharges of tonic firing motor units.