A three year old maiden mare was submitted to daily transrectal examination in order to describe the clinical alterations of ultrasound images of the uterus and ovaries during the oestrus cycle. It was concluded that the diagnose of the oestrus cycle phases in the mare means ultrasound is feasible taking into consideration the number and size of follicles, the presence and morphology of a "Corpus luteum" and the uterine wall characteristics.
oestrum cycle; ultrasound; mare
