Spontaneous congenital heart malformations in Sprague Dawley rats.

The incidence rate of spontaneous congenital cardiac defects in Sprague Dawley rats has not been extensively studied. The incidence of general congenital defects in these animals has been thoroughly investigated and is very low. We sought to determine the prevalence of congenital heart defects in Sprague Dawley rats. Teratology studies using mammalian models have become increasingly important as the number of known environmental contaminants has increased; thus, it is essential to know the incidence of spontaneous congenital cardiac defects in this most commonly used mammalian model so that statistically appropriate research protocols can be planned. Using a thorough method of evaluating the structure of the heart, 624 Sprague Dawley fetal rat hearts were examined just before parturition. Animals used in this study were control groups for surgically manipulated, hydrocarbon-treated animals in a study by Dawson et al. in 1990. The overall incidence of spontaneous congenital cardiac defects was found to be 2.3%. This is similar to the incidence of congenital cardiac defects in humans and thus enhances the suitability of Sprague Dawley rats as a small mammalian model to study the factors that affect cardiac development.