Herniation of the liver through the diaphragm in Mol: WIST rats

The occurrence of herniation of liver through the diaphragm in Mol: WIST rats from toxicological studies conducted over a period of approximately 15 years at the Institute of Toxicology, National Food Agency, Denmark, is described. The incidence of diaphragmatic hernia in male rats indicates a tendency toward an increase through the years. The long term carcinogenicity studies initiated in 1971, 1976 and 1982 (age of the rats at necropsy approximately 2 1/2 year) revealed no diaphragmatic hernias in the 1971 study and 4% in both the 1976 and the 1982 study. In females, 0%, 1% and 1% respectively with diaphragmatic hernias were found. Among the animals from two one-year studies, only with male rats, initiated in 1985 and 1987 respectively, 7% and 5% of the males had diaphragmatic hernias.