Pre-Foaling Management (Book Excerpt)

From: Chapter 17: Pre-Foaling Management

A mare should be brought inside at night beginning 30 to 45 days before her due date. This is done for two reasons. The first is so she can become comfortable with the surroundings and feel that the foaling stall is a safe, private place. Mares that are not at ease might delay foaling and prolong their labor until they feel more secure. Such a delay can lead to complications.

The second reason is to introduce the mare to all the local pathogens, giving her time to build immunity and concentrate this immunity in her first milk, or colostrum. The foal receives all its immunity for the first three or so months of its life via the antibodies absorbed from the mare's colostrum during the first 24 hours of life. By introducing the mare to the local organisms ahead of time, you are, in effect, protecting the foal.

The foaling stall should be a minimum of 14 x 14 feet, have solid walls that rise at least three feet from the floor, be free of any sharp edges, and be well ventilated but draft-free. The stall should be kept clean, dry, and well-bedded at all times. The mare should be isolated from transient horses (show and sale horses) and young horses (weanlings and yearlings) to avoid exposing her or her unborn foal to any new and/or particularly virulent pathogen (rhinopneumonitis in particular). Ideally, foaling mares live in a separate barn and get turned out during the day in small compatible groups of five or six.

Normal mares in the late stages of pregnancy benefit greatly from daily exercise and should have ample opportunity to get out and move around freely in good weather. Daily walking helps decrease the buildup of pitting edema in a mare's legs and abdomen during late gestation. It also helps her maintain good muscle tone, an advantage when it comes time for delivery.

The mare ideally has a clean, grassy paddock or field where she can readily be observed in case she decides to foal during the day. A grassy location, free of manure buildup and cleaned by the elements, is a fine place for a mare to foal provided the weather is dry and not too cold. This probably offers a much cleaner environment than her stall. If the mare foes foal in a field, it is important for her and the foal to be safe from other horses and to deliver where she will not hurt herself or lose her foal under a fence or into a body of water (tank or pond).

When mares are first brought into their stalls a month or so before foaling, they should be checked for the presence of a Caslick's in the vulva. Mares that have had a Caslick's procedure to prevent pneumovagina need to have them opened before delivery. Because mares can foal unexpectedly, open a mare's Caslick's when she begins to show signs of increasing udder development or two weeks before her due date, whichever comes first. A mare that attempts to foal through a closed Caslick's in all likelihood will deliver the foal but will tear her perineum severely.

Make sure the mare has up-to-date vaccinations at this time. As already stated, the mare concentrates antibodies in her colostrums for the immune protection of the foal. Vaccinations given 30 days before foaling should be tailored by a veterinarian to meet whatever disease problems are typically encountered in the area. Having said this, however, it is prudent to vaccinate all foaling mares for tetanus, east and Western encephalitis, and influenza. (This regimen is in addition to the rhinopneumonitis prevention regimen of vaccinations for herpesvirus at three, five, seven, and nine months of the gestation.)

Continue deworming programs throughout pregnancy. Make sure to administer anthelmintics that are safe for pregnancy and avoid organophosphate and phenothiazine dewormers.

From Chapter 34: Stallion Management

General considerations for good stallion management are maintenance of the stallion in excellent health and a stress-free environment that promotes normal sexual behavior and sperm production. The size and construction of housing for the stallion is generally a matter of personal preference. However, stallions should not be maintained in complete isolation but should be able to see mares and other stallions. The type of housing used for stallion in Central Kentucky would appear to be ideal. The majority of these stallions are maintained in a barn containing several stallions, but each stallion has his own paddock separated from adjacent paddocks by double fencing. This allows a stallion to have considerable exercise and interaction with other stallions.


The requirements for exercise vary considerably with the individual stallion. Some stallions, given the opportunity, will exercise freely to the point of weight loss. Lazy, more complacent stallions might have to be force-exercised by lunging or hot walking. Exercise maintains a stallion in good bdoy condition so that he does not become too fat. Excess fat on a stallion will insulate the testicles and could affect semen quality. However, the major reason for exercise is to prevent boredom and maintain a good mental attitude and sex drive. Signs of boredom can include stall weaving, cribbing, and aggressive behavior. Some less-aggressive stallions can be maintained in a barn that also houses mares. At Colorado State University, stallions are housed in 12 by 12-foot stalls and alternate being turned out in 12 by 36-foot runs. Many farms invest significant money to ensure the safety and comfort of the stallion, as well as to provide attractive surroundings for promotion of their stallion.


The nutritional requirements of the stallion vary, depending upon his size, condition, work load, and temperament. During the breeding season, the work load for a stallion is greater than that of a performance horse, and, therefore, the stallion should be fed as an animal under heavy work conditions. This would include a good quality roughage at 2 percent to 3 percent of body weight, as well as 0.5%- 1% of a grain ration. An alternative would include adequate pasture supplemented by a good-quality hay, grain, and salt-and-mineral mix. During the non-breeding season, the stallion generally can be given maintenance ration. Typically, breeding stallions are overfed, which can affect their sex drives and seminal quality. The need for vitamin supplementation has not been documented for the stallion. In fact, supplementation of vitamins A and E had no effect on sperm production. Stallions also should be placed on a routine vaccination and deworming schedule. It is important that the stallion be given proper hoof and dental care as well.

From Chapter 5: Reproductive Examinations

Breeding mares is sometimes a humbling experience. Many mares seem to take perverse delight in outsmarting their managers and veterinarians, almost as if to say, "So you think you have it figured out? Watch this!" on average, mares will demonstrate receptivity for five to seven days, and we know they will likely ovulate during the last 24 to 48 hours of the heat. But accurately predicting exactly which day a given mare will ovulate can be difficult, especially if no records exist of her behavior and reproductive tract parameters on previous cycles.

One strategy to combat the unknown is to breed a mare every 48 hours during her heat cycle, beginning on the second day of receptivity, until she is no longer receptive to the stallion. This strategy is based on the knowledge that the average fertile stallion's semen will last in the mare's tract for at least 48 hours and that she will begin teasing out within 24 to 48 hours of ovulation. Therefore, breeding her every 48 hours during her heat increases the likelihood that fertile sperm will be waiting to fertilize the oocyte when the ovulated oocyte arrives in the oviduct. There are drawbacks to this approach, however, especially an increased likelihood of the mare developing a uterine infection. Semen is not sterile, and every breeding introduces contaminants and bacteria as well as sperm into the uterine lumen. Well-conformed, healthy, young mares are adept at clearing this contamination in a timely fashion and are less likely to become infected as the result of breeding. Older mares, mares that have anatomical differences that incline them to pneumovagina and/or pooling vaginal urine or uterine fluid, and mares that have cervices that remain somewhat closed and fail to relax completely during estrus have a much more difficult time clearing contamination and are likely to develop an endometritis/uterine infection following breeding. For this latter class of mares, multiple breedings during a heat cycle are contraindicated.

With heavily booked stallions (especially in live cover scenarios) it might not be possible for a mare to get in to be bred more than once during a given estrus. Likewise, for logistical reasons, it sometimes is difficult to obtain numerous semen shipments when breeding artificially with shipped semen (it also becomes quite expensive), and frequently the number of available breeding doses is limited when dealing with frozen semen breedings. For these reasons the breeding management goal for each mare is to breed her in front of, and as close to, ovulation as possible to limit the number of breedings necessary.

When the timing is right on the mark (i.e., she is bred less than or equal to 48 hours before her ovulation), she will need to be bred only one time during the cycle, which is the ultimate goal of the breeding management. When breeding based solely on the mare's behavior, one effective strategy for some farms with exceptionally good and careful teasing management is to breed mares on the third day of their behavioral estrus, then once more on the fifth day if they continue to tease strongly. Because most mares ovulate sometime on or between the third and fifth day of estrus, this method can be quite effective for mares that show heat well and reliably. A more intensive breeding management approach is to combine serial teasing of a mare with serial rectal examination of her reproductive tract via direct palpation and ultrasonography. This method provides direct information about the structures on the mare's ovaries as well as the tonal quality of her uterus and cervix. The combination of this information and the mare's teasing behavior considered on multiple, sequential examinations throughout the heat provides a much more accurate picture of how the mare is progressing through her estrus and therefore a more valuable method of predicting her ovulation and the best time to breed her. Mares are crafty enough that it always behooved the examining veterinarian and mare manager to have as much information as possible on which to base their breeding decisions. It is time and money well spent because it will save both in the long run by decreasing the guess work and increasing the likelihood that the mare will successfully become pregnant on a limited number of attempts.

Breeder's Guide to Mare, Foal, and Stallion Care was written by Christine Schweizer, DVM Christina Cable, DVM, and E.L. Squires, PhD.

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