Horse Pregnancy

The period of pregnancy in the mare is about eleven months. Determination of pregnancy can be made in three ways:

  1. Conformation. The conformation of a horse is the key to its progression. Conformation is basically the way the horse has been put together. The body should be in pleasing balance with the limbs and should be well-proportioned. The horse is a working animal and its working ability is determined by the condition of its limbs and feet. Poor conformation of limbs may contribute to lameness.
  2. Laboratory Testing. There are two types of tests: blood tests which are done between sixty and ninety days after service, and a urine test which is done between two hundred and two hundred and seventy-five days after service.
  3. Manual Testing. This is done by a veterinarian who examines the mare internally via the rectum. This requires considerable experience and dexterity if it is to be carried out with any degree of accuracy. An early indication can be given at twenty-one days, although a final legal decision is not possible till six weeks into the pregnancy. This is called a 42-day pregnancy test, on which a certificate may be issued.

Ultra Sound Scanning

This is a non-invasive technique which is harmless to the operator and the mare. An electronic probe sweeps the area under examination. Echoes, produced as the beam scans the various organs, provide a clear, moving image on a display screen. Accurate diagnosis of pregnancy can be made as early as 14 days after ovulation.
Manual and ultra-sound testing gives a much quicker result and allows time for rebreeding if the mare is not in foal; the other tests are used if there is any danger to the vet, the mare or the fetus in manual testing (for example, very highly strung mares, or mares that abort easily).

The Hours Before Birth

Between six and forty-eight hours before foaling, a small amount of clear thick, serum-like material oozes from each teat canal (there are two can alsper teat in the mare). This serum hardens to a wax-like material, and once this appears most mares will foal within the following twelve to twenty-four hours. But some mares show little or no wax. A particular mare will usually be constant in her foaling procedure and any unusual behavior should be recorded, especially where the mare is not seen to wax at all.
Vulvas of sutured mares should be cut at least a week before the foal is due, to prevent tearing.
In most mares the pelvic ligaments show slackening twelve to eighteen hours before foaling. A hollow appears on either side of the root of the tail and the tail loses its power to hug down over the perineal region. Unfortunately, however, mares do not always follow rules. A mare can appear days off foaling when examined at midnight, and yet have a foal several hours old at her side at dawn.


During the first stage of labour the mare may paw the ground, look at her flank, kick at her belly, crouch, catch her breath or wander uneasily around—and then resume feeding. This may be repeated in ten to fifteen minutes. From this point on, the mare should be kept under supervision. It is preferable to keep out of sight and not to interfere unless there is an obvious emergency.
There are no fixed rules for the act of foaling. Most mares lie on their side to foal, raising the upper hind leg at each contraction. At this stage the labour pains, which have been intermittent and of short duration, become intensified and succeed each other at shorter intervals.
When the cervix has relaxed sufficiently, the contractions will force the fluid-filled membranes through the vulval lips of the mare. About five minutes after the appearance of the water bag, the first leg appears and the bag bursts, discharging about 4 liters of placental fluid. After a short rest the second leg appears 8-10 centimeters behind the first. Never pull on the less-advanced leg in an attempt to level it with the first, as this invariably results in fractured ribs for the foal. Both feet should appear with the soles facing the mare’s hooves, and the foal’s muzzle between the knees. Any other combination of the above, such as head only, or soles up, requires a vet immediately, as the foal is probably presenting abnormally.
One of the most important conditions to prevent is the recto-vaginal fistula, where the foal’s foot ruptures the roof of the vagina and tears it longitudinally as the mare strains. This will be evidenced by a leg being caught in the roof of the vagina, and possibly even the appearance of a hoof through the anus. In this case a sterilized, lubricated hand should be placed in the vagina around the offending leg and the leg pushed towards the mare’s head and redirected into the vaginal cavity. This should be done immediately the problem is noticed. This condition is most common in young mares foaling for the first time but may also occur in older broodmares with deep bellies. Repair of the tear is a complicated surgical procedure requiring skilled veterinary attention.
Occasionally the mare will expel her foal until its hips become wedged in her pelvis. In this event she needs help, and delivery must be made quickly or the foal will be lost.
the foal slowly from side to side. If this is not successful. the attendant should pass a sterilized, lubricated hand into the birth canal, over the rump of the foal and grasp the tail. A hard pull on it as the mare strains almost always brings the foal.
Allow the umbilical cord to tear of its own accord about 3-5 centimeters from the navel.
If the mare has not passed her entire afterbirth within three hours of foaling it should be considered retained placental membrane. A vet can apply medication to help the mare pass all of the membrane and contract the uterus.

Do’s and Don’ts

  • Don’t hurry the mare or hover over her.
  • Don’t touch the mare or foal while the labour is progressing normally—that is, let the mare foal as decreed by nature.
  • Don’t hesitate to call your vet if the mare is in trouble. Trouble is indicated by the mare straining for more than one hour without the appearance of the foal; the appearance of the head and no feet, or the head and one foot, or the feet and no head. Once normal foaling begins the foal is born within 15 minutes of the appearance of the feet. if waiting for help, keep the mare walking, provided the foal is not hanging out.
  • Make sure the membranes over the foal’s nostrils are torn; if this does not happen by the time the head is out, quickly tear them away with your fingers.

‘Foaling heat’

According to most data, the average gestation period for thoroughbreds is about 340 days. Data indicate that colts are generally carried longer than fillies. Disease can influence the length of gestation. Normally, the mare has a ‘foaling heat’ soon after the birth of the foal, usually on or about the ninth day. This is usually a short estrus, but the mare will accept the stallion and, under favorable conditions, will conceive. If the mare has had a rough foaling with evidence of bruising and hematomas of the birth canal, it is advisable not to breed at this time, nor should a mare that has foaled for the first time be rebred at foal heat, as she is more likely to have suffered damage.
Some breeders hesitate to breed on the ninth day for several reasons:

  • The mare showing signs of estrus may not be near ovulation.
  • There is a possibility of uterine infection.
  • Traumatic injury to the birth canal often goes unnoticed.
  • The womb of a mare kept in a box for nine days after foaling has rarely contracted properly, and while there may not be infection the presence of secretions and retained debris is unfavorable for conception.
    For these reasons, routine genital examinations at the seventh or eighth day after foaling are indicated. If the mare is not mated on foal heat she will normally cycle again eighteen to twenty-one days later. Failing this, it will be fifty to sixty days.

After Foaling

Always spread the membranes out on the ground and make sure both uterine horn tips are present. Many mares who retain the afterbirth for more than three hours will have difficulty conceiving at the next foaling heat. Never pull the membranes out manually, unless under veterinary supervision. Keep the membranes for your veterinary surgeon to examine.
The following should be carried out after foaling:

  • Enema for foal (100 milliliters of warm soapy water).
  • Navel swab of tincture of iodine.
  • Shot of wide-range antibiotic to both mare and foal, especially if there is a history of infection.
  • Tetanus anti-toxin or toxoid, to both mare and foal.
  • Drench of 4.5 liters of mineral oil for the mare to prevent post-partum colic. Repair of episiotomy (cut vulva) or tears.
  • Wash mare’s hindquarters with disinfectant.

If the mare fails to lick the foal and show it affection, a little table salt rubbed on the foal’s neck and shoulders may help. A little of the dam’s milk rubbed on the foal’s muzzle and face may overcome resentment. A mare should be supervised until she thoroughly accepts the foal and allows it to suckle. On rare occasions this may take as long as a week, in which case tranquilization may be used to allow the foal to suckle. Very rarely a mare may reject the foal so savagely that it is best to bring the foal up by hand,if a suitable foster-mare cannot be found. Consideration should be given to culling such a mare from the breeding program.

Horse Weaning

Weaning can take place between four and seven months. The guiding factor should really be the dam’s condition. For instance, a fat mare with plenty of milk can suckle her foal for six months or longer, particularly if she is empty (not in foal again) and therefore does not need to nourish a fetuses well. A day or two before separation, accustom the mare to having her udder and teats gently handled and milked.
On the morning selected for weaning, the mare should be walked to her new paddock leaving her foal behind in its usual box with both upper and lower doors shut. It is important that the foal is strictly confined in a safe enclosure, which must have solid high walls. The mare should be placed in a sturdy yard well out of earshot of the foal’s cries. The mare’s udder should be inspected twice a day and she will need to be milked to relieve the pressure. Do not strip her out completely as this only stimulates further milk secretion and production.