Spring is the traditional time of year for breeding on most horse ranches. Horses are long-day breeders meaning that natural reproductive activity peaks during the longer days of the year. Generally, from mid-spring through the summer mares regularly cycle every 21 days.
With the elimination of the horse slaughter market in the U.S. the economics of horse breeding has suffered substantially resulting in a decrease in the number of mares bred each year on most farms. However, for those who are still in the business of getting mares in foal there are a number of things to consider to maximize success. The first step is to consider the general health of the mare. A complete physical exam in conjunction with a reproductive exam performed by your veterinarian is an excellent place to start. Healthy mares in good body condition and on an excellent plane of nutrition are more likely to get pregnant. Spring is a great time of year for booster vaccinations, implement a good deworming strategy and consider other health maintenance procedures such as teeth floating. During the reproductive portion of the exam your veterinarian can assess the mare’s reproductive tract, determine whether or not she appears to be cycling and foresee any potential risks or difficulties in getting the mare pregnant. An ultrasound examination of the uterus and ovaries can yield invaluable information regarding the health of the reproductive tract and stage of the estrous cycle.
Once the mare passes examination, there are several methods of breeding to consider. Pasture breeding, in which the mare is turned out with a stallion for a period of time is a low-labor method of breeding but does not allow the manager/owner much control over time and frequency of breedings and can also pose a greater risk for injury to the mare or stallion. Hand breeding, in which the mare and stallion are both under restraint at the time of breeding and the stallion is brought to the individual mare at each breeding is commonly practiced and allows for more control by the owner/manager. Often mares are bred every other day while in estrus. Artificial insemination using fresh-cooled or frozen semen is also very common. Ultrasound examination allows for proper timing of insemination. A.I. provides the advantage of access to remote stallions of superior genetics. Embryo transfer is often reserved for the most valuable of mares. Embryos can be flushed from genetically superior mares and then transplanted into surrogate mares. This allows a single mare the potential to produce multiple offspring in a single year.
Young healthy mares often need little assistance but with age and complications come a need for more veterinary involvement. The use of technologies such as ultrasound, uterine culture and/or biopsy as well as tailored intrauterine therapy or hormonal therapy can dramatically improve success and in some cases make possible the potential to get your mare in foal this spring.
Darren Loula, DVM, is owner of Christian County Veterinary Service, LLC, a mobile large animal vet clinic.