This study was performed to investigate the reproductive performanceand spontaneous malformations of female Sprague Dawley (SD) rats obtained from the Animal Resource Unit, Institute for Medical Research for their use in reproductive toxicity assessment. Onehundred and thirty-five virgin female rats with a body weight ranging between 190 g and 210 g were randomly caged overnight with 60 fertile male rats in 1:1 basis. Vaginal smear was performed the next morning and the day of sperm positive was considered as estational day (GD) 0. On GD21 caesarean hysterectomy was performed to examine the outcome of each pregnancy. The female fertility index (sperm positive) was 90.5% and the pregnancy index was 100%. Thepercentage of pre and post-implantation loss were 1.96 and 7.48 respectively with the number of early resorption out numbered the late resorption (0.56 ± 1.0 and 0.36 ± 1.5 respectively). Out of1,234 foetuses examined, only 5 foetuses (0.41%) presented with gross congenital malformation. The female SD rats obtained from the Institute demonstrated high fertility and pregnancy indexes with lowincidence of resorption and malformation, therefore suitable to use for reproductive toxicity assessment.

A one year old, non descript doe presented with the history of straining to deliver and hanging of ruptured water bag from the vulva was diagnosed as dystocia. The attempts for manual extraction of foetus were failed and a dead emphysematous male foetus was removed by caesarean section. Hydrocephalus and prognathism were observed in the dead foetus. The doe uneventfully recovered postoperatively.