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How to Predict When a Mare Will Foal

How to Predict When a Mare Will Foal Most deliveries transpire smoothly with no ill effects. But when a problem does occur—even a simple issue such as an easily correctable dystocia (difficult birth)—things can go south rapidly.

For some breeders, the waiting game starts as soon as the mare is inseminated. For others, it starts when she’s confirmed in foal. Still for others, it starts when she her belly grows large. Whenever that waiting game starts, all breeders want to know: When will my mare foal?

Igor Canisso, DVM, MSc, PhD, Dipl. ACT, Dipl. ECAR, previously of the University of Kentucky Gluck Equine Research Center and now an assistant professor of equine theriogenology at the University of Illinois College of Veterinary Medicine, offered some tips on how to predict when a mare will foal.

Most deliveries transpire smoothly with no ill effects. But when a problem does occur—even a simple issue such as an easily correctable dystocia (difficult birth)—things can go south rapidly, Canisso said. Additionally, “in certain situations, we don’t want let the foal suckle on its dam due to risk of developing a condition such as neonatal isoerythrolysis,” or acute hemolytic anemia caused by ingesting antibodies in the mare’s colostrum and milk that are directed against the neonate’s red blood cells, he said.

“That’s why each foaling should be attended,” he explained. “If there is a simple problem, it can easily be corrected by an experienced foaling attendant. Or, if there is a more serious condition, the mare can be referred to a clinic, or a veterinarian can be called to check the mare.

“Usually, it is best not to wait (to call the veterinarian), as after 30 minutes from ‘water break,’ every 10-minute delay in foaling decreases the foal’s survival rate by 10%,” Canisso said.

And because the vast majority of foalings take place between 6 p.m. and 6 a.m., he said, it’s important to know when you might want to start brewing coffee for overnight foal watches.

Here are some of the options owners and veterinarians can use to predict when a mare will foal.

Estimated Foaling Date—The average equine gestation length is between 335 and 345 days. So you should be able to easily calculate your mare’s estimated foaling date if you know when she was bred. For example, if your mare was bred on Feb. 10 and has an average gestation, you can tentatively expect a foal between Jan. 12 and Jan. 22 of the following year. Canisso cautioned, however, that gestation length varies substantially between breeds, time of the year (it’s usually longer when the mare is due to foal in the late winter and early spring), and individual mares, so use this method only as a guide.

If you’re unsure of when your mare was bred, your veterinarian can perform an ultrasound exam to estimate the mare’s stage of pregnancy and calculate an estimated foaling date.

Physical Signs—As the mare’s due date approaches, start watching for physical signs indicating she’s preparing to foal, including:

  • Tailhead relaxation—Canisso noted this is harder to identify in overweight, heavily muscled, or maiden mares;
  • Vulva relaxation and elongation—Canisso cautioned that some older mares might have very pronounced vulvar relaxation well before foaling while others mares will show minimal or no appreciable changes, so don’t rely solely on this factor to predict foaling; and
  • Mammary gland enlargement—Canisso said most mares’ mammary glands will begin getting larger about a month before their due date, with the most notable changes in the last two weeks prior to foaling. Maiden mares might not show substantial udder enlargement until close to parturition, he said.

Canisso cautioned that maiden mares might not display the same physical signs as seasoned broodmares.

Mammary Gland Secretions—For the last three decades many veterinarians and breeders have used mares’ mammary gland secretion electrolyte levels to predict foaling. In the normal mare, the mammary gland secretion’s calcium and potassium levels rise while sodium decreases closer to foaling. However, measuring these electrolytes to predict foaling requires a machine to analyze the levels and serial measurements. Canisso said that, commonly, breeders and veterinarians have submitted these electrolyte samples to a laboratory, which can be expensive and prohibit the practice’s use for mares not located close to a laboratory–essentially, most mares in most regions.

Because calcium is the most reliable and commonly used electrolyte, commercial kits are now available for breeders to use to estimate the mammary secretions’ calcium carbonate content and, thus, help predict when the mare will or will not foal. The commercial calcium carbonate test’s limitations include the costs and required dilutions to obtain an accurate reading, said Canisso.

Recently, Canisso and colleagues tested another method by which to predict foaling using mammary gland secretions. This time, however, they measured the secretions’ pH levels. Using commercially available pH test strips, owners can test the mammary gland secretions once daily; when the normally slightly basic secretions (pH> 8) drop to below 7 on the pH scale, the mare will likely foal within 24 hours, Canisso said. In his recent study, 11 of 14 mares foaled within 24 hours when their mammary gland secretion pH levels were 7 or lower; the remaining three study mares foaled without significant pH changes, he said.

In the same study, Canisso and colleagues compared the secretions’ pH levels with their calcium, sodium, and potassium concentrations. They found that the pH measurements were equally as effective as electrolyte measurements at predicting foaling, suggesting that pH can replace electrolyte measurements, he said. Canisso also noted that measuring pH is advantageous over electrolytes because the tests cost less; are more practical, as no dilutions are needed to determine pH; and require only a small drop of secretion to complete—this is especially beneficial for maiden mares, he said, as many maiden mares have a very small amount of pre-foaling mammary gland secretions, making electrolyte measurement very difficult.

Electronic Devices—Next, Canisso described some electronic devices breeders can use to alert them to impending foaling:

  • The Foal-Alert is a magnetic device that a veterinarian sews into the mare’s vulva. When the magnets are separated as the vulva expands during foaling, an alert is sent to a pager or cell phone, or an alarm sounds in the barn. Canisso said while this device can be used successfully, it can also cause many false alarms. Additionally, the alarm might not sound if the foal is malpositioned in the uterus or if its feet don’t penetrate the mare’s vulva.
  • The Breeders’ Alert is a position-monitoring device shaped like a small box that attaches to the mare’s halter and sounds an alarm when it detects that the mare is in lateral recumbency (the position in which they deliver a foal) for more than 15 seconds. Like the Foal-Alert, Canisso said, this device causes a lot of false alarms.
  • The last device Canisso described is the Birth Alarm. Like the Breeders’ Alert, the Birth Alarm monitors a mare’s position; however this device is located on a surcingle. When the mare lies down for more than about 8 seconds, an alert is sent to the individual monitoring the mare. As with the other two devices, Canisso said this can throw false positives, and it might be cost-prohibitive for some breeders.

Video Monitoring Systems—Finally, Canisso noted that many breeders and veterinarians employ video monitoring systems that allow them to keep an eye on the mare for signs of foaling from afar.

So which method should breeders select? Canisso said many breeders opt for a combination of the available options to give themselves the best chance to accurately predict when a mare will foal.

“Since there isn’t a single and perfect way to predict foaling in all mares, the best approach is to combine different strategies to maximize the results,” he said.

ABOUT THE AUTHOR

Erica Larson, News Editor

Erica Larson, news editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.

Foaling Horses: 101 to 911

Foaling Horses: 101 to 911

Keep a close eye on your newborn foal, his vitals, and his environment, and always get veterinary assistance if something goes wrong. When in doubt, ask your veterinarian, and never take “wait and see” approach. Photo: Anne M. Eberhardt/The Horse

During and after foaling are two of the most critical times in a neonate and his mother’s lives. One little thing gone wrong could set off a potentially life-threatening cascade of events for either horse. Rissa Parker, BVSc Pret, from Glen Austin Equine Clinic, in Gauteng, South Africa, has had a special interest in mare and foal care for the past 24 years and shared her first-hand knowledge of how to identify normal vs. emergency situations with attendees at the 2014 Cape Breeders Club Seminar, held Jan. 27-28, in Stellenbosch, South Africa.

Parker first described the three stages of foaling:

Stage 1 begins when the foal starts to position itself for birth within the mare’s womb. Parker said signs of this first stage of impending parturition in the mare include restlessness, kicking at the abdomen, lifting the tail, sweating, urinating, and rolling as if colicking. While these signs might be distressing to an owner, Parker said there’s nothing to fear unless they carry on for more than an hour. At this point, consider it an emergency and call your veterinarian immediately.

Stage 2 is the presentation of the foal. At this time the mare’s water breaks, and she delivers the foal. This stage occurs rapidly, said Parker—within about 10 to 30 minutes. Consider anything longer to be an emergency requiring veterinary attention, Parker said. After 30 minutes, “for every 10 minutes that go by, there’s 10% less chance of the foal surviving,” she noted.

If everything progresses smoothly, however, Parker advised owners to clear the foal’s nasal passages and then sit back and watch. The foal’s umbilical cord should break spontaneously as he becomes active. “Do not cut it,” Parker urged. “This can cause bleeding and infection.” Any bleeding from the umbilical cord is an emergency, she said.

If the cord breaks properly on its own, treat it with a chlorhexidine-alcohol spray three times a day for two days, then two times a day for two more days, Parker said. Any hemorrhaging, patent urachus (urine dripping through the umbilicus), or edema (fluid swelling) in the umbilical region warrants a quick call to your veterinarian.

If you observe discoloration of the placental surface (seen here) or holes in the placenta, call your veterinarian right away.Photo: Courtesy Dr. Rissa Parker

 

Stage 3 includes the passing of the placenta from the mare. This typically lasts one to three hours, but if it continues any longer, consider it an emergency. With a slow-to-pass placenta, Parker suggested administering oxytocin to help it “let go.” But do not, however, try to pull the placenta out yourself. “This can leave minute amounts of villi (the small, vascular projections that attach the placenta to the endometrium) still in the uterus,” Parker warned. If the placenta does not pass or a piece of it remains in the mare, she can develop endometritis (uterine infection).

If the placenta passes without problem, examine its horns and body thoroughly to ensure the horn tips are intact and that its weight, color, and integrity are normal. If you observe discoloration of the placental surface or holes in the placenta, call your veterinarian right away.

“The placenta reflects the uterine environment the foal was in,” Parker said. It should weigh less than 11% of the foal’s body weight—any more than that might indicate edema or other problems; these high-risk foals require blood tests and monitoring to ensure they are not septic or compromised and to tackle the problem early.

Examine the amnion for signs of inflammation before discarding it. Photo: Courtesy Dr. Rissa Parker

Parker added that some owners throw away the amnion (placental membrane) without checking it first, but said it’s important to examine this part for amnionitis (inflammation of the amnion which occurs in certain disease syndromes resulting in fetal losses).

Post-Partum

After parturition, Parker said it’s very important to allow the mare and foal to bond. But first, wash the mare’s udder and legs as soon as possible. Foals have a tendency to suckle on anything they can while learning to nurse, and they can easily pick up any bacteria on the mare. After this, just sit back and observe, Parker said. Watch that the foal is breathing, that he attempts to stand within one hour, and that he nurses within about three hours (any longer than this is a cause for concern).

“The foal must drink within four to six hours,” she explained. “Suckling aids gut motility as well as colostrum (the mare’s antibody-rich first milk) absorption.”

Although it might seem like an obvious task, she emphasized the importance of watching the foal nurse. Horses have a natural fight or flight instinct; for a foal this often manifests as cowering with his head under the mare’s belly. Parker said at first glance, it might appear as if the foal is nursing, when in reality he’s not. To determine whether he is truly getting milk, check the fullness of the mare’s udder (if it’s very full, he’s probably not drinking), and seek veterinary assistance if needed.

Foals that don’t consume enough good-quality colostrum (seen here) are at risk of failure of passive transfer. Photo: Courtesy Dr. Rissa Parker

Why is it so important the foal suckles? Because if he doesn’t consume enough colostrum from his mother’s first milk, he is at risk of failure of passive transfer (FPT), said Parker. To determine whether your foal has achieved passive transfer, have your veterinarian measure his IgG antibody levels within the first 24 hours of life. More than 800mg/dl is adequate; 400-800 mg/dl is partial FPT; and less than 200 mg/dl is complete FPT. Parker said she typically treats foals with FPT with a plasma transfusion and antimicrobial administration if the foal shows signs of sepsis.

Signs of Trouble

Parker also described signs to look for in the foal that might indicate a problem needing veterinary attention. First, know how to recognize normal foal vital signs, including:

  • Temperature between 38-38.9°C (100.4-102.02°F);
  • Heart rate 40-80 beats per minute (bpm) initially, increasing to 130/150 bpm in the first week and then decreasing to 60-80 bpm after that; and
  • Respiratory rate greater than 60 breaths per minute during the first hour, decreasing to 20-40 breaths per minute after the first one to two hours.

Once you have these core measurements down, look for signs of the following common neonate issues:

  • Meconium impaction Clinical signs of an impaction of these first feces include straining, bloating, colic signs, and an absence of suckling. “If the foal is bloating, take him off the mare so you are not filling up a dysfunctional gut,” Parker said. She said her typical treatment includes a noncommercial enema using an acetylcysteine base (which breaks down the disulfide bonds that make the meconium so hard and sticky) and warm water for 20 minutes under sedation.
  • Ruptured bladder Because this condition can be life-threatening, make sure your newborn foal urinates a full stream, keeping in mind that the bladder might not even become full for two to three days. “Foals with ruptured bladders show signs of abdominal distension and anuria (the absence of urination),” Parker said. Transport affected foals to a surgical facility for correction.
  • Diarrhea Although common in foals, veterinarians don’t always know what causes diarrhea, Parker said. This is yet another reason why it’s so important for owners and breeders to stand back and observe the neonate, taking into account his age, vitals, habitus (when the foal is quiet, such as eating or sleeping), and drinking/hydration. Diarrhea causes can be infectious (e.g., from viruses such as corona or bacteria such as Escherichia coli or Rhodococcus equi), noninfectious (e.g., due to overfeeding, lactose intolerance, pica [consuming nonfood items]); or parasite-related (Strongyloides westerii).

    Parker cautioned that, when it comes to infectious diarrhea-causing agents, “we underestimate how much we can transmit disease ourselves. It’s good practice to have a box of disposable gloves at your farm for handling newborns.”

    Diarrhea treatment includes resting the foal’s gut by withholding milk, but not water, for 24 hours. Your veterinarian might then recommend feeding 50 ml of milk every 4 hours to feed the enterocyte cells that line the horse’s gut, administering Bio-Sponge (Di-tri-octahedral smectite) to line the gut, and feeding the foal salt (1 tsp twice daily) to replace lost sodium.

    “If the foal isn’t suckling or has a high temperature, it’s an emergency that requires veterinary attention which may then include antimicrobial administration and intravenous fluids,” Parker said. “Sequelae to diarrhea include lactose intolerance, patent urachus, and joint ill (infection), so you’re not completely out of the woods (after diarrhea subsides).”

  • Musculoskeletal issues Foals can be born or acquire conditions such as congenital limb deformities and lameness due to infected joints or limb injuries, all of which require veterinary attention. So pay close attention to your newborn’s lower limbs as well.

Take-Home Message

Keep a close eye on your newborn foal, his vitals, and his environment, and always get veterinary assistance if something goes wrong. When in doubt, ask your veterinarian, and never take “wait and see” approach—it could be the difference between life and death for your foal.

ABOUT THE AUTHOR

Alexandra Beckstett, The Horse Managing Editor

Alexandra Beckstett, Managing Editor of The Horse and a native of Houston, Texas, is a lifelong horse owner who has shown successfully on the national hunter/jumper circuit and dabbled in hunter breeding. After graduating from Duke University, she joined Blood-Horse Publications as Assistant Editor of its book division, Eclipse Press, before joining The Horse.

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