Tips to Predicting a Foal's Arrival

Familiarity with the foaling process and your mare is crucial to predicting birth, but you also can employ sensors, alarms, and video monitoring systems.

The act of foaling by a mare is nothing short of explosive. Contractions are fast and powerful. Within minutes, if all goes well, a confused-appearing little horse is lying on the floor of a stall and an exhausted mare is resting quietly. If things go awry during this explosive process, handlers and veterinarians normally have only minutes in which to resolve the problem.

As a result, there have been many efforts through the years to predict just when foaling will occur so that attendants can be ready and waiting.

Research has provided tools and approaches to help accurately determine the time of foaling. Some of them work well, but none is foolproof. Mares don't read manuals and sets of instructions with specific directions. For them, foaling is an individual act. They don't all have the same length of gestation. They don't all give off the same signals when foaling is about to commence, and there are differences in the length of time involved in the act itself.

How to Predict

There is no one predictor that can tell attendants exactly when a mare will go into labor, says Pat McCue, DVM, PhD, Dipl. ACT, associate professor in the Department of Clinical Sciences at Colorado State University's (CSU) veterinary school. The best approach, he says, is to combine observation of physical signs with some of the technology that is available.

To totally understand what is being observed, one must first be aware of the three stages of parturition. We start with the basic fact that the average duration of gestation in the mare ranges from 335 to 342 days. That being said, there have been instances where foaling has occurred prior to 335 days and well past 342 days. The range can actually be from as few as 305 days to as many 400-plus. Here is a basic explanation of what occurs during the process itself:

Stage 1 can involve some vague and nonspecific signs. Most mares will be restless during this stage. They are apt to walk around the stall and some snatch a mouthful of hay, while others might not eat at all. A mare might lie down, roll, get up, stomp her back feet, and even kick at her abdomen. Some of the signs displayed are akin to those demonstrated when a horse is suffering from colic.

One of the reasons for the discomfort is the foal is being positioned for delivery. In layman's terms, it involves rotating from a position where it is lying on its back to where it is on its stomach with the front feet pointed toward the birth canal.

While the foal is changing position, the mare's cervix is dilating to provide access into the birth canal. Just before the mare goes into serious labor, she normally will sweat around the shoulders, flanks, and chest.

Stage 1 ends with the rupture of the chorioallantoic membrane (breaking of the water bag, or the outer layer of the placenta). The fluid that gushes forth serves to lubricate the birth canal, which facilitates passage of the fetus.

That all being said, we must return to the individuality of mares. Some mares might exhibit Stage 1 signs for a day or two--or even several days--prior to foaling. This is where good recordkeeping can be valuable. Mares tend to repeat a foaling routine year in and year out. Thus, if one knows how the mare acted during foaling last year, odds are it will be repeated this year. If she is delivering her first foal, it is highly important that all of the signs and data be recorded for future review.

Stage 2 is the actual birth stage, and it often lasts only 20 to 30 minutes from beginning to end. This is the explosive stage. In normal situations, the fetal placenta will separate from the uterus during the birthing process. The fetus will continue to receive oxygen from the mare's blood via the umbilical cord. This is where a birthing problem can occur. As the foal is squeezed through the birth canal, the umbilical cord is compressed and the oxygen supply can be compromised. There is always the danger of suffocation if the foal is not born quickly.

The foaling attendant will be watching for a normal presentation. This means that the front feet emerge first, one about three to four inches in advance of the other. This expedites passage through the birth canal. The foal's nose will be at about knee level. Hopefully, the amnion, a transparent placental membrane immediately surrounding the foal, will have ruptured. If it has not and still covers the foal's head, it should be torn to enable the foal to breathe. The foal's back feet often remain inside the mare for some minutes after the rest of the body has been expelled. Normally, the mare will lie quietly resting, as will the foal.

Stage 3 involves expelling of the placenta and its associated membranes, also called the afterbirth. This is an important time, as far as the mare's health is concerned. A retained placenta can be very toxic. If it is not expelled within two to three hours after birth, veterinary help should be sought.

Applying What You Learned

By becoming familiar with the three stages of foaling, the attendant becomes more aware of what should happen as the mare is preparing to give birth.

McCue emphasized that it is important to observe the entire range of physical changes in a mare's body as she nears parturition. Udder development should be monitored or clues about her parturition timetable: there will be changes in the teat ends as they fill with milk, there will be "wax" or dried colostrum on the teats, and there are changes in the vulva as it becomes more relaxed.

"I tell my students, 'Don't hang your hat on any one thing,' " McCue says, "but normally, one strong indicator that foaling is close is waxing."

For about 90% of foaling mares, he says, waxing is followed within 24 to 48 hours by foaling.

Again, a problem with this method of prediction arises because of the fact that mares are individuals, and what is normal for one might not be normal for another. The problem is with the 10% that don't conform to the normal pattern of waxing.

There will be a percentage who don't wax at all, McCue says, and there also will be a percentage in which waxing is not followed by foaling within 24 to 48 hours. However, the fact that 90% will foal within 24 to 48 hours after waxing provides a standard for the majority.

Other Foaling Indicators

Here are some other general timetables for physical signs that appear as a mare approaches her due date. Distention of the udder might start up to six weeks ahead of foaling, but it normally begins more like two to four weeks ahead, and teats normally start to fill a week to 10 days prior to foaling. Relaxation of the vulva often is observed 48 hours prior to foaling. A slackening of the area around the base of the tail often begins one to three weeks before foaling.

The technological advances in predicting foaling have ranged all the way from determining electrolyte changes in the mare's milk to alarm systems that sound a warning when a mare goes into labor.

McCue says that CSU foaling attendants make use of test strips and alarms. The test strips are the outcome of a scientific discovery that approximately 24 to 48 hours before foaling, calcium concentration in the mare's milk increases. Some of the researchers found that these changes normally occurred in the evening. As a mare's assumed foaling time nears at CSU, McCue says, her milk is tested each evening.

He says while testing the milk is important, it also accomplishes something else. The foaling attendant is forced to handle the mare up close and personal rather than just observe her from a distance and, thus, is better able to note telltale signs such as udder development and condition of the vulva.

The companies that manufacture test strips to measure calcium in the milk recommend testing begin 10 days to two weeks prior to the expected foaling date. They also advise the test be administered one to two times daily. When the calcium concentration reaches 200 parts per million, reports one of the companies (FoalWatch), birth is imminent. When the mare's calcium concentration reaches 300 to 500 parts per million, they add, birth is usually very near.

Testing the milk involves getting a small sample of milk from the mare and using special kits that the companies provide to measure the calcium levels.

In the test strip approach, color changes in the strip indicate increases in calcium levels.

Once one has predicted foaling within the 24- to 48-hour framework, it is possible to make use of other technology to let attendants know when labor begins. One of the methods utilized at CSU, says McCue, is Foalert. The system relies on a transmitter and a separate receiver. The transmitter is stitched to the edge of the mare's vulva. A tiny magnet is stitched to the other side and is attached to the transmitter. When the mare goes into labor and the vulva lips separate, the magnet is pulled from the transmitter, which activates the receiver, and a remote alarm sounds to alert attendants.

There are various degrees of sophistication with the system, including a telephone hookup and long-range capability.

The system has been most useful during the daytime hours at CSU, according to McCue. "At night we have dedicated foal-watchers, but during the day, many of these people are doing other tasks and the alarm system can alert us."

Research has demonstrated that the vast majority of mares foal at night. Behaviorists seem to think this is a throwback to mares' natural desire to conceal themselves from predators during a vulnerable time.

Other alarm devices are on the market as well. They are designed for activation when the mare lies down and remains lying down, such as would occur during foaling. The devices can either be attached to the mare's halter, or they are worn like a surcingle around the girth.

There also are video monitoring systems that allow you to watch the mare in her stall from the warmth and comfort of your home. Today there are video cameras that can send signals remotely, so no hard-wiring is necessary.

Video surveillance also allows you to avoid "bothering" the mare by your arrival and turning on lights to check her every hour or so. Some mares seem to "put off" foaling until they are alone, and most foaling attendants and breeders can tell you stories of foals they missed, despite monitoring the mare closely.

One company, AVtech Solutions, offers a monitoring system that allows you to access your wireless camera's video over the Internet.

Cameras can send signals in black and white or color. These types of systems have become more commonplace and less expensive in recent years. Some systems also allow you to record events for an archive that can be kept with your files.

Take-Home Message

Technological developments can be helpful in predicting foaling, but only if they are utilized in conjunction with ongoing observation. You need to keep records on your mares to understand their normal pre-foaling attitudes and behaviors, learn early signals that labor is impending, and be available to help if needed. If you are not an experienced foaling attendant, make sure you have a veterinarian or equine midwife who can arrive quickly in case of problems.

About the Author

Les Sellnow

Les Sellnow is a free-lance writer based near Riverton, Wyo. He specializes in articles on equine research, and operates a ranch where he raises horses and livestock. He has authored several fiction and non-fiction books, including Understanding Equine Lameness and Understanding The Young Horse, published by Eclipse Press and available at or by calling 800/582-5604.

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