Eleven months is a long time to wait for the birth of a foal. Even with the best of care, things can go wrong and interrupt the normal development of the fetus and/or compromise the health of the mare.
When the day (or as is often the case, night) arrives for the mare to give birth, it is a time for both anticipation and anxiety. When the two forelimbs protrude from the birth canal, followed by the nose, then the shoulders, the torso and back limbs, it is a time for jubilation whether the birth takes place on a farm where 100 foals are born annually or whether the birth is a singular event.
Conversely, when the mare has difficulty in the birthing process, it is a time for anxiety and appropriate, but deliberate, action or the culmination of 11 months of waiting will be supreme disappointment.
While we routinely describe a mare's gestation period as 11 months in length, that isn't necessarily true. Normally, the gestation period will be from 335 to 342 days, but gestations as short as 305 days and as long as 400 days have been recorded with normal foals produced at both ends of the spectrum. The time of breeding can have an effect. Mares that conceive during late winter and early spring, on the average, will have a gestation period 10 days longer than those whose gestation began in late summer. In one study, when mares were subjected to 16 hours of light each day beginning Dec. 1, the gestation periods were an average of 10 days shorter than in control mares.
Though there is disagreement on the issue, some researchers are of the opinion that male foals are carried significantly longer than females.
Regardless, there comes a time when the mare is set to give birth and the hope of every mare owner, manager, and attendant is that nature will handle the task without the need for intervention. The good news is that nature does get it right about 95% of the time.
It's the other five percent, when something goes wrong and the foal stubbornly refuses to make an appearance, that gives mare owners and veterinarians fits.
There is a word that is used to describe prolonged or difficult births, and it is one no mare owner cares to hear or use.
Dystocia takes a variety of forms, but before one begins to analyze them, it might be well to review what transpires in a normal birthing process.
It happens in three stages. As described by Hugh Behling, DVM, whose practice encompasses the general Louisville, Ky., area. The three stages go something like this:
In the latter days of gestation, the sacrosciatic ligaments of the mare gradually relax, changing from a tight, cord-like consistency to a softer more resilient texture. The ligaments are at their most relaxed just hours before the mare gives birth. Often, this relaxation can be observed as a sunken area on either side of the tailhead. In addition, there is a relaxation, elongation, and enlargement of the vulva, though this is sometimes subtle and difficult to detect. Some hours before parturition the mare will have "waxed up" and may even have milk dripping from the teats.
As labor begins, the mare becomes restless. She lies down and gets back up, sometimes turning to look at her flanks. This is the beginning of labor and it was all set into motion by her hormones whose actions are directly opposite of what occurs in most other farm animals. Unlike most other farm animals, the mare's progesterone levels rise and estrogen levels fall as parturition nears.
Progesterone levels continue to increase right up to parturition itself, then plummet immediately after the birth of a foal. Estrogen levels in the mare reach their zenith between 200 and 250 days of gestation and begin a slow, but steady, decline after 250 days. This decline continues until parturition with the mare once again near baseline levels.
The prime stimuli for the mare's uterine contractions are prostaglandin and oxytocin. There is a definite rise in prostaglandin secretion during the first stage of labor and an explosive rise in the second stage as the foal passes through the cervix. Distention of the vagina stimulates the release of oxytocin and, like prostaglandin, there is a major increase as the foal enters the birth canal.
When the Stage 1 process begins, the foal is lying on its back in the uterus with its head pointing toward the rear of the mare. Before a normal birthing can begin, it must make a 180-degree turn, winding up on its stomach with its head cradled on its two forelimbs. While the foal plays an active role in getting itself turned over, much of the work is handled by the mare through uterine contractions. It is during this process that several things can go awry, but more about that later.
At this point, in addition to the other obvious signs of discomfort, the mare may be sweating, with damp spots appearing behind the elbows or at the flanks.
During Stage 1, the mare is not straining to push the foal into the birth canal. Stage 1 involves getting the foal properly aligned, and it may go on for up to six hours, or even longer. During this time the mare may do much more than ordinary tail switching, and she frequently will stretch as if to urinate. She may also pass small amounts of fecal matter with some frequency.
Sometimes the mare will even attempt to roll in her attempt to get the fetus properly positioned.
During this process her cervix dilates. The first stage of the birthing process ends as the properly positioned foal passes through the cervix into the birth canal, with forelimbs extended and head nestled on top of them. At this time the outer wall of the placenta ruptures (water breaks) as it is forced through the cervix and there is a flood of amniotic fluid which lubricates the mare's reproductive tract.
By now the mare is in labor and normally is lying on her side. Up to this point, time is not of the essence. Now it is. Things have to proceed rapidly from this point on if we are to have a normal birth. Because of the power in a mare's abdominal muscles, Stage 2 may last only 10 minutes and should not go beyond 30 minutes.
In a normal presentation, the first thing visible is transparent bluish-white amnion that encases the foal. (The outer wall of the placenta that ruptured to release the amniotic fluid is the allantois chorion. The foal has remained encased in its own protective covering, the amnion.) Next come the forefeet, with one extended beyond the other. There is a reason for this. By having one foot extended, the foal's shoulders are angled a bit, making for easier passage through the unyielding pelvic area.
Next comes the nose and head, with the neck lying extended along the forelimbs. Shortly thereafter, the shoulders, torso, and hips make their appearances and the foal is lying behind its dam with the umbilical cord still attached. This isn't the time to hassle the mare and try to get her up immediately. Blood is still being pumped through the umbilical cord. If it is broken prematurely, it may cost the foal as much as a pint of blood that will wind up draining into the placenta.
The final stage in this real life drama involves passing of the placenta and involution of the stretched uterus. If all goes well, the mare should pass the membranes within an hour. When all three stages of the birthing process flow into each other, it is like a well-rehearsed orchestra making smooth transitions from one movement to the next.
Most of the time, all does go well, but four to five percent of the time it doesn't. Many dystocia problems can be solved, but others become so severe that all one can hope for is saving the mare's life.
The most common cause of dystocia by far, says Behling, is malposition of the foal. Malpositioning, Behling estimates, accounts for the majority of all dystocias, while uterine and placental malfunction or infection account for the rest.
Unfortunately, there are few indications that a dystocia is in the offing. Frequently, the first indication manifests itself when the mare is already in intense labor. Dystocia also carries with it a sinister connotation. Very often, says Behling, the root cause, particularly when malpositioning is involved, is a problem with the foal. It may be dead, for example, or there might be twins, or it may be suffering from another malady, such as wry neck or contracted tendons.
Malpositions most frequently encountered and remedies utilized to solve them are:
One front leg folded back--When the mare begins pushing the foal through the birth canal, only one leg, instead of two, will be protruding. If one were to grasp the leg at this point and begin tugging, serious damage could result to the birth canal.
To solve the problem, one must get the fetus pushed back out of the birth canal so that the forelimbs can be repositioned. This is more easily done if the mare is on her feet rather than on her side straining. To make certain the free leg isn't "lost" in the process, Behling suggests that a loop of sterile rope or an obstetrical strap be placed around the protruding leg before the repulsion is begun.
Once this is accomplished and the mare is on her feet, the looped leg and the head are pushed backward into the uterus. When the foal has been repulsed from the birth canal, it is time to reach in with the other arm to find the malpositioned leg. Once it is found, it is grasped just above the knee and gently manipulated into proper position. No traction should be applied until the legs are properly aligned.
Once both legs are in proper position, a sterile rope or obstetrical strap can be slipped around the pastern of the leg that had been out of position. Once both legs and the head are correctly positioned, the mare normally will lie down once again and quickly give birth.
Both forelimbs flexed backward, or elbow lock--Behling uses a comparison with a diver in describing this condition. "Basically," he says, "it is as though you were to take a diving position and then dropped your elbows, while your hands remain in the same position as you attempt to go through a small opening. Your hands will be attempting to get through first, but your elbows will lock into place and movement is stopped."
This condition will identify itself with the head showing up in the birth canal, minus the forelimbs. The remedy involves getting the mare on her feet so that gravity can lend a hand in getting the foal back into the uterus. The procedure then is to use a hand to follow the foal's head and neck to the shoulder and then on down to the leg. In addition to being a practical way to find the legs, this method also provides an element of safety. One will be certain that the limbs being dealt with are the forelimbs and not the hind limbs.
The next step is to place sterile ropes or obstetrical strap around the pasterns of each of the forelimbs and pull them gently into position, in line with the head and neck. An effort should be made to follow nature's approach in delivery, with one forelimb extending beyond the other so that there is a slight angle to the shoulders, making for easier passage through the pelvic area.
Wry neck--In this case the front legs will make an appearance, but there will be no head, because it is folded back along the foal's body. "With wry neck foals," says Behling, "the foal has developed abnormally and the neck is just like a rubber band and wants to lay back on the shoulder."
Again, the prescribed method for resolving the problem is to get the mare on her feet and push the foal backward. When the head is discovered, a loop of sterile rope or cord is passed over the lower jaw to provide a means for pulling the head into proper position. In some instances, this will be successful, but Behling says that often the only way to remove a wry neck foal is via Caesarian section or fetotomy (dismemberment of the foal surgically).
Dog sitting position--As with wry neck, the dog sitting foal has not developed normally. In the beginning of the birthing process it might look like a normal delivery with the front feet and nose appearing. The danger signal involves having the front feet and nose followed by a back foot.
"Normally," says Behling, "you are not going to get the dog sitting foal out without doing a C-section or fetotomy."
Upside down foal--When the front feet of a foal make their appearance and the soles are pointing up instead of down, the foal is beginning the birth process upside down.
There are two ways the problem can be solved--either rotate the foal or help with the delivery as presented. The dangers involved in turning the foal include puncturing or lacerating the uterine and vaginal walls, but they are outweighed, says Behling, by the nearly impossible task of delivering the foal when it is upside down.
If one decides to help deliver the foal as presented, the procedure involves applying traction in a downward manner with both hands on the forelimbs until the shoulders are clear. At that point, the next step is to get both hands inside the birth canal and onto the back legs so they can be held to full extension during the remainder of the delivery. If the back legs are not held into position in that manner, there is danger that one of them could be raised and rupture the uterine or vaginal wall. While that approach sounds good in theory, Behling says, it is not a procedure he would recommend. Every effort, he said, should be made to rotate the foal into the correct position.
Hip lock--This form of dystocia often takes attendants by surprise because it occurs just at the moment when everything seems to have gone just fine. The front legs and head will have made their appearance, followed by the shoulders and torso.
Suddenly, all movement stops. The foal is hip-locked. The prescribed solution is to cross the front feet and push backward, thus exerting a slight twisting action on the foal's body. Often, this will immediately free up the hip lock and the foal will slide free. If it doesn't, the legs are switched and the foal again is pushed backward in a twisting manner until the hips are freed.
Accentuating to the hip lock problem, Behling says, is the fact that by now most of the natural lubrication of the birth canal has been used. A shortage of natural lubrication is a concern with most dystocias, Behling said, and the attending veterinarian must be prepared to provide liberal amounts of artificial lubricants to assist the foal in sliding through the birth canal.
Head lodged beneath the pelvic rim--While this form of dystocia isn't all that common, it does occur. For some reason, the head leaves its normal position atop the forelimbs and drops down, lodging the nose beneath the mare's pelvic rim.
The prescribed procedure, says Behling, is to repulse the forelimbs until one can slide a hand beneath the foal's chin and forcibly elevate it to the proper position atop the front legs.
Breech birth--The most uncommon form of dystocia, says Behling, is the breech birth. It is also among the most difficult to deal with.
In some cases, the foal's back legs will make their appearance first and in others, it will be only the tail that can be detected. The prescribed solution when only the tail is visible is to repulse the foal and attempt to get both back feet into the birth canal. Once that is accomplished, the rest of the birthing must proceed quickly because there is danger that the umbilical cord will become compressed against the bony pelvic area, shutting off the foal's supply of oxygen.
Quite frequently, says Behling, breech foals are dead and that accounts for the position they are in. If it is impossible to remove them through traction, he said, the only solution may be fetotomy.
"One of the prime problems with malpositioned foals," Behling says, "is cervical tears. There is also the danger that a stray foot will rip through the birth canal wall and penetrate the rectum. Damage to the reproductive tract involves a long recovery period and surgical repair may be required. In a number of traumatic cases, the damage may result in a barren mare and, worst case scenariao, can cause death."
Damage to the reproductive tract also results when undue traction is applied by attendants during the birthing process. "This is not the time for strongman heroics with ropes and chains and three people pulling," Behling says. "About all the pressure you should apply, and it should be in a downward manner, is what two people can exert."
And, he added, traction should only be applied in concert with the mare's contractions. When she relaxes to catch her breath, unless a breech birth is involved when the foal must be removed very quickly, the handlers should cease their downward traction. Conversely, when seeking to repulse a foal, the pushing action should only be employed when the mare is between contractions.
It is also a given, he said, that anyone inserting a hand or arm into the birth canal should first have scrubbed thoroughly with disinfectant to avoid contaminating the mare with harmful bacteria. The same is true of any ropes, cords, or obstetrical straps--all should be sterilized before being used.
In some instances, he said, mares resolve malpositioning problems themselves. It is for this reason that the mare in Stage 1 gets up and lies down frequently, he explained. She is helping the fetus to properly position itself. During Stage 1, time is a positive element because the foal is obtaining its oxygen through the umbilical cord and requires no outside source.
"If need be, you can walk that mare for an hour," he said, "with no harm to the foal from lack of oxygen."
It is during Stage 2 where the umbilical cord can become compressed, that there is a danger of the foal losing its oxygen supply before it can breathe on its own.
A form of dystocia that leaves the veterinarian with little choice of procedure, says Behling, is the foal that simply is too large to pass through the birth canal. In that case, a Caesarian section is about the only remedy available. Drastic cases call for a fetotomy.
More often than not this problem will surface with the young, immature filly that has been bred to a large-framed stallion.
Still another cause of dystocia is uterine inertia. In these cases, the uterus simply refuses to contract. The identifying signs include a mare whose water breaks, but who then has few or no contractions.
There is little to do, except to delve into the uterus and attempt to pull the foal free, says Behling. Sometimes grasping a leg and giving a tug will set off contractions, but in other instances, the whole birthing process must be carried out manually. Again, the problem will be accentuated by a lack of normal lubrication in the birth canal.
As with limb positioning efforts, Behling said, care must be taken to avoid lacerating the reproductive tract when delivering a foal whose dam has uterine inertia.
After The Foal
Unfortunately, dystocia often has a negative effect on Stage 3 of the birthing process--passing of the placenta.
Causes for placenta retention stemming from dystocia include trauma to the uterus and delayed uterine involution; secondary uterine inertia as the result of myometrial exhaustion from the prolonged birthing process; and disturbance of the normal uterine contractions as the result of getting the mare on her feet and walking her while attempting to properly align the malpositioned foal.
Whatever the reason, a retained placenta is extremely dangerous to a mare's health. Because the blood supply to the uterus has been shut down, the placenta very quickly degenerates with harmful toxins and bacteria being released by the decaying tissue. "Plus," says Behling, "you have bacterial contamination from the birthing process, so you are facing the very strong possibility of contamination and infection of the uterus."
One of the unsavory after effects of a retained placenta can be laminitis. In a study at Texas A&M University, 51 mares with severe dystocia were referred to university hospitals. Of that number, 69% followed dystocia with a retained placenta, and 22% developed laminitis.
Along the way the mare with a retained placenta can also develop severe metritis (inflammation of the uterus), wherein the wall of the uterus becomes thin and very fragile or even necrotic.
The first weapon to be called into use when a placenta is retained, says Behling, is oxytocin. Doses can range from 20 to 120 units and may be administered by your veterinarian intravenously, subcutaneously, or intramuscularly. These treatments can be repeated every few hours. Usually, in the wake of oxytocin injections, the mare will show signs of abdominal discomfort followed by straining as intense uterine contractions begin, and the retained placenta will be expelled.
More often than not, Behling notes, the spot where the retained placenta is held firmly in place is the nongravid uterine horn (the one that did not house the fetus during gestation).
If oxytocin does not produce contractions sufficient to dislodge the placenta, the practitioner may have to manually massage it free. This, says Behling, is a ticklish job that must be handled with care to prevent damage to the uterine wall.
The uterus is at its most vulnerable immediately after the fetus is expelled. At this point, it is a huge, empty, thin-walled pendulous organ. When the mare stands up after giving birth, the dangling membranes often open the vulva, admitting a rush of air into the uterus.
Uterine vulnerability at this point adds urgency to timely delivery of the afterbirth so that the uterus can quickly begin involuting toward its pre-pregnancy state.
Once the placenta is expelled, a quick examination of the membranes by a veterinarian will reveal whether it has been expelled in its entirety or whether a portion has been retained. The examination also provides information about the general health of the placenta, which very well may have a bearing on the health of the mare as well as the newborn foal.
An inflamed-appearing placenta may be a sign that the mare has suffered from placentitis, and this could mean the foal is born septic because it will have been bacterially infected while housed inside the damaged placenta.
It is incumbent upon mare managers and owners, Behling says, to keep a close watch for any vaginal discharges during pregnancy which might indicate placentitis. If such signs occur, the recommended treatment is to place the mare on antibiotics immediately.
"It is extremely important that there is no infection of the placenta during pregnancy," Behling says. "I've maintained suspect mares on antibiotics for as long as 30 to 40 days prior to foaling to make certain infection of the placenta had been cleared up and that it remained uninfected and healthy."
A problem of long standing in regard to fetal health has been the ingestion by mares in the last trimester of pregnancy of endophyte-infected fescue.
"The endophyte, which is like a mold," says Behling, "is very toxic to a mare's placenta. Not only does it often prolong gestation to 12 and 13 months, but the blood supply to the fetus is also compromised. This can result in foals that don't have suckle reflex or over-sized foals. There is an 80% to 90% mortality rate among foals where the mare's placenta has been damaged by toxins from the endophyte."
The preventive measure to take, he says, is to make sure pastures are mowed regularly during the summer and to prevent the mare from ingesting endophyte-infected fescue during the last three to four months of pregnancy.
While the owner has no control over preventing some types of dystocia, he said, the form stemming from infected fescue is easily controlled.
After one has taken the necessary steps of keeping mares off infected fescue in their last trimester and treating for visible signs of placentitis during pregnancy, matters are pretty much in nature's hands.
When the birthing process begins, the role of the attendant, says Behling, is to be present, but unobtrusive. In 95% of the cases, the mare will handle things just fine by herself. In the 5% of the cases where dystocia occurs, the person attending the birth should be capable of recognizing distress signals immediately and informed enough to take remedial action at least until professional help can be summoned.
Time is of the essence.
"If you are attending a foaling and suspect a problem," Behling says, "don't wait. Call for professional help immediately."
About the Author
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 www.exclusivelyequine.com or by calling 800/582-5604.
POLL: Colic Surgery