Horse Breeding, Reproduction & Foal Care

The wide-spread use of transported semen in horses has opened the opportunity for mare owners to breed their mares to top stallions very economically without their horses leaving their control by going to breeding farms for months on end. While this presents huge opportunities to breed to top stallions, it does require extra commitment on the part of the mare owner which involves monitoring their mare’s estrus cycles at home.

We encourage mare owners interested in breeding to start charting their mare’s estrus cycle as early as possible in the breeding season. Record observations of when the mare appears to go into season and when she goes out on a calendar. Actually, the hardest part of breeding with transported semen is anticipating the mare’s estrus cycle and ovulation period. In mares that are very predictable, this is much easier than in mares who are less obvious about their heat cycles. In mares that do not clearly manifest outward signs of estrus (heat), there are procedures that your EVA veterinarian can use to take control of the mare’s cycle and bring her into a breedable heat cycle with a high degree of predictability.

When searching for a suitable stallion, always inquire about the shipping policy and specifically inquire if semen was shipped for this particular stallion the previous year. If it was, ask for the conception rates for the previous year. The answers given will give you an idea of what kind of success you can anticipate, as well as an indication of the professionalism of the provider on the shipping end of the program. An answer like “This % got in foal on the first shipment, this % conceived on the second shipment and overall this % of mares we shipped to last year were pronounced in foal”, is a much more comforting answer than “ We don’t really keep track” or “ I will have to look it up “ or, even worse “ Hey Mabel! Did any of those mares we bred Junior to last year get pregnant?”

Even if we do everything right on the receiving end, and the shipping end does a poor job, the outcome may be disappointing. Be aware that serious delays and expenses can mount up with inexperienced shippers or with stallions that have not shipped semen successfully in previous years.

Once the mare is in season, one or more trans-rectal ultrasounds will be done to monitor the development of follicles on the ovaries. If there are not stocks available to restrain the mare, it is often necessary to sedate the mare to protect the ultrasound equipment and the veterinarian.

Depending on the lead time requested by the stallion owner, often 48 hours, semen is shipped and the mare is artificially inseminated with one or two doses depending on what is provided by the shipper. Quite frequently, the mare is given an injection after breeding to encourage the egg to ovulate thereby increasing the odds of conception.

The first pregnancy check is usually done at about 16- 18 days later. If the mare has not conceived, then she will likely be coming back in season at that time and there will be adequate time to order semen and attempt for a pregnancy on that heat cycle

There are several pregnancy checks done on a mare during early pregnancy. These checks are done to make sure that the pregnancy is progressing normally, and to quickly determine if a termination has occurred while it is still possible to rebreed the mare during that breeding season. It is very frustrating to have a positive pregnancy check at 18 days, and then when the mare is not looking fat 9 months later to discover that she lost the foal early in the pregnancy.

Once the mare has passed the 60 day mark, there is a high likelihood that she will carry to term, assuming that she gets rhinopneumonitis vaccinations at 3, 5, 7, and 9 months of pregnancy. Appropriate vaccination for rhinopneumonitis is one of the most important things a mare owner can do to prevent abortion in their mare.

Pregnant mares are wormed normally and can be exercised normally up until their last 60 days of pregnancy unless special circumstances develop. One month before their due date, it is customary to do a pre- foaling check of the mare and to do booster vaccinations on the mare in order to maximize immunity which will be given to the foal through the mare’s colostrum.

There is no substitute for experience when foaling out a mare. Fortunately, there are many videos on the internet where individuals have videoed their mares foaling which can serve as a great primer. Be aware, many mares prefer privacy, so keep visitors and the “carnival atmosphere” to a minimum, or it is likely you will miss the entire show. Mares can foal very quickly, and will often do so when everyone just leaves for a “few minutes”. It is not unusual for the mare to get up and down several times while repositioning the foal for delivery, but if she is pushing hard and is not making progress with the delivery, it is time to call the on call veterinarian for advice.

Normally, a healthy foal will stand within one hour of being born, will nurse the first time within two to three hours and the afterbirth should be expelled by the mare within six hours post foaling. Any significant deviation from these parameters should result in a call to the veterinarian.

If all goes well, it is customary to do a neonatal exam and draw blood to check for adequate colostral immunity in the baby after the foal is 24 hours old. The foal is checked for evidence of early infections, congenital defects and the mare and afterbirth are examined for potential abnormalities

Contact Us

For more information regarding horse breeding in Orange County, please contact Equine Veterinary Associates by using our online contact form or call office at 714-777-3942.