When your favorite basketball team is leading by a point and the clock is ticking down to the final seconds with your team in possession, time seems to move at a snail's pace. Not so when your favorite mare is in labor and can't seem to deliver a foal. Then, so it seems, time speeds along like a rocket. In both instances, time is of the essence. In a basketball game, it might mean the difference between a conference championship or just another ordinary season. When a birthing is involved, the stakes are higher. Time can make the difference between a live foal or a dead one, and even between the survival or lack of same on the part of the mare.
"Dystocia (difficult birth) in the horse is one of the few true emergencies we encounter in which minutes make a difference in the survival of the patient (the foal)," says R. L. Embertson, DVM, a surgeon at Rood and Riddle Equine Hospital near Lexington, Ky. "Fortunately, dystocia occurs in only approximately 4% of foaling mares."
And, when it does occur, often the attending veterinarian or the farm's foaling crew can assist in such a way that the mare is able to deliver a live and healthy foal.
However, there are times when on-the-site help has exhausted all possibilities and the mare must be transported to an equine hospital for further assistance.
All the while, a deadly clock keeps ticking away the seconds.
The birthing process in horses creates something of a good news, bad news scenario. The good news is that parturition occurs very rapidly, so mares are spared a long and debilitating labor. The bad news is that when something goes wrong, there is very little time to correct it before the life of the foal is placed in serious jeopardy.
Normally, the second stage of labor--the period of time beginning with the rupture of the chorioallantoic membrane (breaking water)--and delivery of the foal encompasses only 20 to 30 minutes.
When the time span hits 40 minutes or more, the survival rate for foals takes a pronounced dip, and if it goes beyond an hour, chances of the mare delivering a live foal become very slim. There are, of course, exceptions, and live foals can be delivered up to 90 minutes after the chorioallantoic membrane ruptures, says Embertson.
Playing the role of "court of last resort" in a dystocia after all efforts at the farm have failed is the veterinary hospital, where practitioners are forced to work against an ever-accelerating clock. Normally, they don't waste time with procedures that already were tried and failed at the farm. Instead, the mare is immediately anesthetized and her rear quarters elevated as part of the procedure to reposition and deliver the foal. And, when all else fails, a Caesarean section will be performed in a last-ditch effort to save the foal and protect the mare.
One of the keys to a successful resolution of dystocia, says Embertson, is early detection of a problem at the farm. It all starts with the attendant in the foaling barn who must be able to quickly recognize the telltale signs of dystocia and seek professional help without delay.
"That is where we have a chance to improve survival rates," says Embertson, "recognition at the farm. Knowing when to send the mare to an equine hospital."
At Rood and Riddle Equine Hospital, a procedure for handling dystocia cases that arrive on an emergency basis has been developed, and it moves along on a precise, rapid, pre-determined time schedule.
While a Caesarean section is always a possibility, it is a last resort procedure. The first 15 minutes after the mare arrives will be spent attempting to remove the foal vaginally.
By the time a mare with dystocia arrives at the hospital, says Embertson, it is assumed that all of the normal remedies for assistance that could be utilized at the farm have been exhausted and have failed. The hospital staff immediately swings into the next phase of help.
"The moment a mare with dystocia walks in here," says Embertson, "she is anesthetized so she isn't pushing against you."
Step number two involves elevating the mare's hindquarters. A combination of a relaxed uterus because of the anesthesia, abetted by the force of gravity, enable the clinician to repel (push the foal back into the uterus) and reposition the fetus.
"The most common problem we have," says Embertson, "involves malposture of the fetus. Frequently the forelimbs will be flexed, or else the neck is flexed with the head back."
When this is the situation, the clinician repels the foal and corrects the malposture problem. The mare is then lowered to a resting position on her side and the foal is pulled out.
However, no one during this procedure indulges in the luxury of operating on the theory that this will always result in a successful delivery. While the mare is in an elevated position, the ventral portion of her abdomen is clipped and partially prepped for a Caesarean section by a crew member, just in case.
Time continues to be of the essence.
"I have an attendant time me," says Embertson. "If I can't get that foal out in 15 minutes, we do a C-section. From the time we make a decision to do a C-section, we should be able to get the foal out in 20 minutes. It takes a lot longer than that to complete the surgery, of course, because incisions must be closed, but we should have the foal out in 20 minutes."
At Rood and Riddle, a trained dystocia team assembles immediately upon learning that a mare in trouble is on the way. When the foal is removed, either through controlled vaginal delivery (CVD) or through Caesarean section, three staff members move in to lend assistance to the foal.
In a paper presented on the hospital approach to treatment of dystocia at the recent American Association of Equine Practitioners meeting in Lexington, Embertson described the procedure this way:
"Different anesthetic protocols have been used successfully for C-section in the mare. The most important factors for foal survival are rapid delivery and immediate neonatal care. Thus, anesthesia should be induced rapidly and kept at a light surgical plane. In our hospital, consistently good results have been obtained with xylazine, followed by simultaneous administration of diazepam and ketamine. The mare is maintained on halothane and oxygen, with ventilation controlled.
"Following delivery of the live foal, the umbilical cord is immediately clamped and transected and the foal is carried to an adjacent room readied for resuscitation of the neonate. A nasotracheal tube is passed if necessary to ensure a patent airway. Oxygen, suction, and an Ambu bag are available if needed, as are emergency drugs, intravenous catheters, and intravenous fluids. The umbilical stump is treated, and the condition of the foal is assessed, with further resuscitation efforts directed where needed."
Normally, says Embertson, the foal will be at least partially anesthetized due to drugs being used on the mare crossing the placenta. If all goes well, the foal often will recover more quickly than the mare and will be waiting for her in the stall.
The incision made to perform Caesarean surgery, Embertson says, is similar to that employed in colic surgery. The difference is that in colic surgery, the incision is made in front of the mare's umbilicus, while in a C-section it is made behind the umbilicus.
"You start the incision just in front of the mammary glands," Embertson explains, "and go forward. Usually, the foal's hind legs are in one of the uterine horns, so the key is to find the uterine horn that has the hind legs and get that exteriorized. Then you make an incision in the uterus at a point between the foal's hind feet and hocks and pull it out backwards. Normally, the head will be at the birth canal and the hind feet will be in a uterine horn."
Once the foal is delivered and turned over to other crew members, the surgeon turns his attention to sewing up the uterus and cleansing the abdominal area to prevent infection.
"Infection is a concern," says Embertson. "You have had your hands inside the uterus and you've normally opened up the uterus outside the abdomen."
Copious lavaging is the first line of protection. The abdominal cavity is cleansed by repeatedly administering fluids and then suctioning them clear, along with unwanted debris. The mare is also placed on antibiotics for three or four days.
Sometimes, says Embertson, the surgeon can pull the placenta through the incision after delivery of the foal, but more often, it is fairly firmly attached to the lining of the uterus and undue pulling produces the danger of tearing.
Most often, he says, he closes the uterus with the placenta still inside, depending on the mare to expel it as she would following a normal birth. Generally, mares will expel the placenta without undue problem, Embertson says, but it often is retained longer than would be the case in a normal delivery. Usually, he says, the placenta is passed in eight to 12 hours following surgery.
The fact that the mare retains the placenta longer than normal might have an effect on her becoming pregnant in the immediate future, he says.
"If we do a C-section early enough in the year," he says, "you have a shot at getting her back in foal that year. But if it is into the middle or late part of the breeding season, it is often best to simply wait until the next year."
The good news is that a C-section normally does not compromise the mare's long-term foal producing capability.
"If you look at the long-term picture," Embertson says, "those mares do get back into foal and they do produce other foals."
Does the mare immediately recognize and accept a foal that she did not deliver normally?
Surprisingly, says Embertson, they almost always do, even though the foal has already been dried off by the time the mare awakens from surgery and is led to the stall.
"I have never seen a mare reject a foal after a C-section," he says.
While the success rate at Rood and Riddle in dealing with dystocia problems that couldn't be resolved at the farm is admirable, the statistics show that odds swing the other way when delivery is delayed, no matter how sophisticated the facility or how proficient the surgeon and crew.
From 1986 through 1994, a total of 80 mares with dystocia were treated at the hospital. Of these, 58 were resolved with controlled vaginal delivery, 20 were resolved by C-section, and two by fetotomy (dissecting the foal and removing it from the uterus in pieces).
Nineteen of 80 foals were discharged from the hospital. Ten of the 80 were born alive, but died or were euthanized (usually because of deformities), and 51 of the 80 were delivered dead.
Of the 58 dystocias resolved by controlled vaginal delivery, 13 foals survived. Of the 20 resolved by C-section, six survived.
The mean time from arrival at the hospital to delivery was 21 minutes (a range from nine to 55 minutes) for a controlled vaginal delivery and 40 minutes (a range from 25 to 70 minutes) for a C-section.
Time is the prime factor. Early detection of dystocia means that there might be time for resolving the problem and saving the foal's life, along with protecting the reproductive health of the mare.
Embertson summed it up this way:
"The increased duration of dystocia is directly related to the decreased chance of survival of the foal. In this review, 64% of the mares admitted to our hospital for dystocia yielded a dead foal. The survival rate for foals from mares with dystocia can be increased by decreasing the duration of each step--the time from chorioallantoic membrane rupture to the time when the need for further assistance during foaling is recognized, the time taken to ship the horse to a referral facility, and the time taken to deliver the foal."
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: University Equine Hospitals