Fetal sexing: Early and late gestation

The development of improved ultrasound scanners has led to detailed images of equine embryos being visible per rectum, and curiosity by mare owners as to the sex of the fetus to help with breeding and management plans has developed steadily. The equine fetus develops a genital tubercle from 60 days of pregnancy, and this is visible with a good quality ultrasound scanner as a hyperechoic ‘equals mark’, either on the lower abdomen between the stifles (colt) or under the tail between the tail bone and the stifles (filly) ...