Canine teratogenesis with an estrogen antagonist

Abstract
A nonsteroidal estrogen antagonist, CI‐628, was administered orally to female beagle dogs on days 1–15 following mating. Dosages of 0.5, 1, 2, and 5 mg/kg effectively blocked pregnancy; six litters were whelped after 0.125 or 0.25 mg/kg in which various defects were present in pups of three litters.