| Preparation for the Breeding Season
R. Paul Schwab, D.V.M. and David Sauter, D.V.M.
Kulshan Veterinary Hospital
Horses are seasonally poly estrus, which means they have a regular heat interval but only during certain seasons. This happens to be during the late spring to late summer when the sunlight is more intense. With this said, preparation for breeding time starts in the fall and winter.
There a many decisions that should go into breeding horses; which mare to breed, which stallion to breed to, will it be a natural cover or artificial insemination, do you have the facilities to do this, and who is paying for everything? For the purposes of this article we will focus on the preparation of the mare and stallion themselves for the breeding season.
As mentioned before, mares are seasonal breeders. During the winter months, when the days are shorter, they normally do not cycle and are not fertile. In the summer months, mares are fertile and cycle regularly, ovulating about every 21 to 22 days. Between the two seasons, mares are described as “transitional.” During these spring and fall transitions, mares have erratic, long heats but do not ovulate and, therefore, are not fertile. Repeated breeding during transitional heats will not result in pregnancy and can lead to reproductive problems.
For various reasons, the equine industry has been interested in developing techniques to move the natural breeding season ahead, so mares will have foals earlier in the year. The best method to date for accomplishing this goal is the use of artificial lighting. Between the natural light and the artificial light, the mare needs to be exposed to 16 continuous hours of light per day. This means the mare must be in her stall with adequate artificial light before dusk. A centrally located 200-watt bulb in a 12-foot by 12-foot stall is generally adequate light. Most breeders simply set a switch timer to go off at 11 PM.
The health of the mare and stallion is probably the most important part of breeding management. Fall and early winter is a good time to evaluate their general physical condition and vaccination status. Special attention should be given to their body condition and nutritional status. Your veterinarian or nutritionist can help in determining your horses’ needs based on their individual situation and metabolism. Also, studies have shown that increasing body condition increases fertility. Obesity, however, is not helpful and may lead to health problems and difficulty with the delivery of the foal later.
If your mare will be traveling to a breeding facility to be bred, find out what vaccines may be needed for that particular region or barn. Most horses should be up to date on Flu, Rhino, and Tetanus vaccination, but it might be helpful to vaccinate for West Nile, Encephalitis, Potomac Horse Fever, Equine Viral Arteritis, or even Strangles depending on the circumstance. If you are a stallion owner don’t forget about how many horses may come to your barn and expose him to various diseases.
In addition to a basic physical exam, a reproductive exam for the mare is helpful. Typical parts of a repro exam include:
· Evaluation of perineal conformation. If the vulva is set high or tilted forward, this can lead to fecal contamination, “wind sucking”, and infections of the reproductive tract. Mares with this problem may benefit from a “Caslick’s” surgery, which closes the upper portion of the vulva.
· Vaginal speculum exam. This procedure allows inspection of the vagina, looking for problems such as uterine discharge, persistent hymen, scarred cervix, and “urine pooling.”
· Uterine Culture. Most breeders require this test. It helps determine whether any infection is present in the uterus. Some uterine infections can be contagious to the stallion.
· Rectal Ultrasound exam. This allows the veterinarian to inspect the entire reproductive tract both by how it feels and how it looks on the ultrasound screen.
· Uterine Biopsy. This is useful for mares that have breeding problems, such as older mares or mares that failed to get pregnant in previous years.
For stallions, the list is much shorter but no less important. Breeding soundness exams on stallions include a general physical exam with special focus on the hind limbs. The testicles are also examined for size and consistency. If needed, semen collection can be done, but it requires some training of the stallion, a mare in heat, and trained personnel.
As the breeding season approaches discuss with your veterinarian and breeder your goals of when you would like the mare bred and how to recognize when the mare is in heat. Hormones are available to assist in estrous manipulation and synchronization and are often needed in cases when artificial insemination is used. Also with the advent of ultrasound, it is easier to determine where a mare is in her estrous cycle. Because a mare can be in heat for 5-7 days, timing breeding at the end of estrus can maximize semen survivability in the uterus. Devoting a calendar to monitor when your mare is in heat and not in heat also increases the chances of breeding her on the right day and avoiding extra time with the stallion.
Copyright © 2008 The NW Horse Source, LLC
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