2.3. Mares and Insemination
Mares (n ¼ 34) in estrus were examined by transrectal ultrasonography at approximately 2-day intervals to monitor follicle size. Seven mares (group 1 had 3 mares; group 2 had 2 mares; and group 3 had 2 mares) that developed a small amount of anechoic intrauterine fluid during estrus were treated once with ecbolic administration
(20 units of oxytocin, intramuscularly [IM] or 250 mg of cloprostenol, IM). Fluid was not detected in any ecbolicallytreated mare on the following day.