The question of when to set up an initial appointment for a reproductive evaluation and subsequent monitoring of the estrous cycle of a mare depends on several factors.
Consideration 1: When do you want a foal?
The first consideration is when an owner wants to begin breeding management and what time of year the foal would be born. Some owners want early foals (January to March) and other owners want to wait until the weather is warmer.
Consideration 2: Is the mare under lights?
A second consideration is whether or not the mare has been under lights. The natural breeding season for a mare is April to October. Maintaining a mare under lights beginning in early December will advance the first ovulation of the breeding season, so that the mare will begin cycling in early to mid-February. Therefore, if a mare has been housed under lights, she could be brought to the Equine Reproduction Laboratory to begin monitoring in late January or early February. In contrast, mares not housed under lights could be brought to the Equine Reproduction Laboratory in mid-March or early April.
Consideration 3: Does the mare have a history of reproductive issues?
A third consideration is if the mare has had reproductive problems or challenges in the past. ‘Problem mares’ should be brought into the clinic in advance of the breeding season so that selective diagnostic tests can be performed to make sure that the mare is cycling and that the uterus is free of infection. This entails an ultrasound examination followed by collection of uterine culture and uterine cytology samples.
Consideration 4: Is the mare currently pregnant?
A fourth consideration is whether or not the mare is currently pregnant. If a mare has a normal delivery (i.e. no dystocia), passes the placenta on time (i.e. within 3 hours and does not have a retained placenta), did not have any excessive bruising or trauma to her reproductive tract and perineal area, and does not have a vaginal discharge beyond the normal 1 to 3 days, an owner could consider breeding the mare on her foal heat. If a foal heat breeding is desired, our clinical protocol would be to examine the mare 7 days post-foaling, determine her current reproductive status and begin the process of monitoring her ovarian function with the intent of breeding the mare at an appropriate time. If an owner does not want to breed the mare back on her foal heat, the mare could be administered a dose of prostaglandins 5 to 7 days after her foal heat and breed on the short-cycled heat or wait until a few days before the 30-day heat to bring the mare in for an examination.
Ideal breeding time
Finally, if your mare is open (not pregnant), does not have a history of reproductive problems and you can tell when she is coming into heat, the most efficient time to bring her into the clinic for reproductive management is the second day of estrus. That would provide sufficient time to perform an ultrasound examination to confirm her follicle status and stage of the estrous cycle, as well as set arrange for breeding in the following 2 to 3 days by live cover or artificial insemination with fresh, cooled or frozen semen.