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Home First Posted Mar 13, 2009
Jul 25, 2010

Gestation and Foaling Tips

Always check with your vet!

To find excellent articles on the following topics please follow this link: Oregon State University Scholar's Archive
  • Managing Your Pregnant Mare and Her Foal
  • Managing Your Pregnant Mare
  • Health care
  • Feeding
  • Foaling preparation
  • Foaling
  • After-foaling mare care
  • Conclusion
  • Managing Foals
  • General foal care
  • Newborn care
  • Colostrum
  • Foal observation
  • Weaning
  • Supplemental nutrition
  • Deworming and vaccinations

The following are a number of helpful facts that may be useful to you regarding breeding your mare:

  • Normal gestation 340 days give or take two weeks..
  • Gestation range can be 310 to 370 days.
  • Warmer weather generally means less time for gestation.
  • Cooler weather generally means more time for gestation.
  • Age can make a difference on due date.
  • First time pregnancy can make a difference on due date.
  • Multiple births generally make a difference on due date.
  • Be mindful of your mare two weeks before her due date.
  • Generally 3 years of age is when the first mating can take place.
  • Window is 21 days (heat and estral cycle).
  • Usual ovulation 24-48 hours before estrus ends; Cycle returns in 21 days, if not bred.
  • You may notice that your mare is "winking" at you. Lift her tail and take a look at her vaginal area.
  • If in with the geldings, your mare may back up to the geldings and present herself to try to entice them.
  • This window for fertilization varies and often ranges from ten to 37 days.
  • Ten to 12 years is the normal fertility time
  • Heat usually lasts up to six days.

How Do You Know When Your Mare May Be Close to Foaling?

  • Milk veins increase in size.
  • Teats change. They tighten up.
  • You will notice a point in the mare's abdomen.
  • Approximately two days before delivery the mare's nipples will get waxy and may also drip milk.
  • The mare's vulva enlarges.
  • There is a visual change in the mare's hips. They drop.
  • When beginning to give birth your mare may exhibit colicky signs: pawing, lying down, biting at her abdomen, kicking at her abdomen, sweating, etc.
  • Provide a safe space for foaling. Create A Safe Foaling Stall
  • Call the vet.

Many people now put in web cams where they can keep an eye on their mare. Also, baby monitors are being used, as well.

The Merck Vet Manual has the following:

Parturition

"Preparation of the Environment:
The mare should be taken to the foaling location 3-4 weeks before the expected foaling date so she can produce antibodies to the pathogens present in the environment. These antibodies will be sequestered in colostrum for passive immunity in the newborn.

Foaling box stalls should be large (at least 3.5 x 3 x 3.5 m). The foaling area should have good ventilation and be well bedded with clean, dry straw. The walls should be solidly constructed and free of sharp edges. Observation of the mare should be possible without disturbance.

Mammary Gland:
Evaluation of the signs that precede parturition is useful but does not permit precise prediction of the time it will be seen. The mammary gland starts developing 3-6 weeks before foaling and distends with colostrum in most mares 2-3 days before parturition. Colostrum drips from the teats and dries to form a waxy material at each teat orifice. This "waxing" develops in ~95% of mares 6-48 hr before foaling, but in some cases, it is not seen at all or it precedes parturition by many days. Before foaling, the calcium and potassium content of udder secretions increase, and the sodium content decreases. Water hardness chemical tests have been used on mammary gland secretions to predict imminent parturition.

Stages of Parturition:
It is critical to understand the normal progression of events during parturition. This permits identification of abnormal events and whether and when intervention is needed. Parturition is divided into 3 stages.

Stage I is characterized by signs of abdominal pain and restlessness due to uterine contractions. Patches of sweat in the flank area and behind the elbows usually appear a few hours before foaling. The uterine contractions increase in frequency and intensity, causing the fetus to move into the pelvic canal, which causes the cervix to dilate. The fetus changes from a dorsopubic to dorsosacral position before parturition. Mares may roll during the first stage, which is thought to facilitate the rotation of the fetus. Increasing pressure in the uterus causes the allantochorion to protrude through the internal os of the cervix. The allantochorion over the cervix (cervical star) does not have microvilli and is thinner than the rest of the membranes. The allantochorion usually ruptures at the cervical star, and this marks the end of the first stage of parturition.

Stage II starts with the rupture of the allantochorion and ends when the fetus is delivered. Labor usually takes 10-30 min. Stimulation of the cervix by the fetus (Ferguson reflex) causes the mare to have abdominal contractions. The allantoic fluid lubricates the canal, facilitating expulsion of the amnion and fetus. Vaginal distention causes release of oxytocin and further myometrial and abdominal contractions. The amniotic membrane appears between the vulvar lips as a white, fluid-filled structure. The straining efforts of the mare consist of 3-4 strong contractions, followed by a short period of rest. The mare usually assumes lateral recumbency during delivery with her limbs extended. The foal is normally delivered in an anterior presentation and dorsosacral position with the head, neck, and forelimbs extended. One front hoof of the foal usually precedes the other by ~15 cm, facilitating passage of the elbows and shoulders through the pelvic canal. The foal is usually born with the umbilical cord intact and covered by the amnion, which is ruptured by movements of the mare or the foal. If amnion remains over the foal's nose, an attendant should remove it to prevent suffocation. If left undisturbed, the mare may lie for some time with the foal's hindlimbs in her vagina. If the foal has not been delivered within 30 min of the rupture of the chorioallantois and release of the tea-colored allantoic fluid, obstetric intervention is warranted.

Stage III involves expulsion of the fetal membranes. Normally, fetal membrane passage occurs rapidly (within 3 hr) after delivery of the foal. The weight of the amnion and cord helps the allantochorion separate from the endometrium. Progressive traction by the amnion and powerful uterine contractions originating at the tip of the horn cause complete separation of the allantochorion, which may become inverted during the process. The mare will stand with the amnion hanging from the vulva at the level of the hocks or below. If the mare kicks, which endangers the foal, the membranes should be tied above the hocks. If the fetal membranes have not been passed by 3 hr after parturition, oxytocin (20 IU, IV or IM) should be administered at 15-to 30-min intervals.

Premature Separation of the Placenta: Normally, the translucent white amnion appears first at the vulvar lips during the expulsion stage of labor. Premature separation of the placenta is characterized by the appearance of the bright red, velvety, intact chorioallantois between the vulvar lips before the foal is delivered. The presence of the chorion at the vulvar lips indicates that it has separated from the endometrium before the foal is able to breathe spontaneously. The chorioallantois must immediately be ruptured and the foal manually delivered, or the foal may asphyxiate. The severity and duration of asphyxia that results determines the severity of neurologic abnormalities displayed by the foal (peripartum asphyxia or neonatal maladjustment syndrome [Hypoxic Ischemic Encephalopathy: Introduction])."

Add the date of exposure and this calculator will give you an estimated due date for your latest foal.
Horse Gestation Calculator

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Horse Coat Color Calculator

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Horse Weight Calculator


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