Abstract
Spontaneous clonic convulsions in the Charles River Wistar rat have been observed at an incidence of 1.5%. Females (2.3%) are more susceptible than males (0.7%). These convulsions are not seen in rats of less than approximately 16 weeks of age. Some animals have exhibited single convulsions whilst others have convulsed on numerous occasions. No histopathological abnormalities of the brain have been recorded for these animals following routine examination.