Elective Cesarean Sections: Who Needs Them?
Many horse breeders and owners are familiar with the circumstances that necessitate an emergency cesarean section. Those circumstances involve the mare and/or unborn foal being in imminent danger due to birthing difficulties (also known as dystocia). Less commonly, though, a veterinarian might recommend an elective cesarean section (C-section) for a non-emergency situation.
As you might know, a C-section is an incision made into the abdomen, then into the uterus in order to remove the fetus. C-sections have been performed in humans since the Roman era and were included in Roman law in order to either save the fetus or to provide for separate burial, says Nathaniel A. White II, DVM, MS, Dipl. ACVS, Theodora Ayer Randolph Professor of Surgery at the Marion duPont Scott Equine Medical Center, Virginia-Maryland Regional College of Veterinary Medicine. Although the name of the procedure refers to a surgical term, some sources, including the Merriam-Webster dictionary, say the term comes from the belief that Julius Caesar was born this way.
Notes White, "We do very few elective cesarean sections. It's something that's done for particular horses, and not without some concern. Consequently, we get questions about the procedure."
Why Elect Cesarean?
One of the most common reasons for this uncommon procedure is because the mare had a fractured pelvis that healed so that the pelvic opening is not large enough to allow the foal to pass through normally. Another problem is a congenital defect that prevents the foal from passing through the birth canal.
"With a pelvic fracture, the mare would be obviously lame," says White. "The veterinarian would confirm the diagnosis via radiographs or rectal examination. After the fracture heals, examination of the pelvis by rectal palpation can determine if the pelvic canal will allow a normal birth."
In the instance of a body or limb malformation of the foal, the surgery is completed to prevent injury to the mare during attempted foaling. The foal is usually not expected to survive or would be euthanized at birth because of its deformities. These deformities are rare and might not be recognized until the time of foaling.
Another reason for a veterinarian to perform a C-section is due to cervical injury. Explains White, "The cervix is the opening into the uterus from the vagina; it's very muscular and normally closed except during estrus and foaling. But in some cases, the cervix can be injured or torn during foaling. If it is, it subsequently may be difficult to get the mare pregnant, or if it's repaired surgically, it can tear again the next time the mare foals. Each time it tears, the ability for the mare to conceive and carry a foal again is decreased."
Veterinarians at the Marion duPont Scott Equine Medical Center performed an elective C-section on the same mare twice because of a severe cervical tear. "The mare was able to get pregnant after surgical repair, but if she attempted to foal normally, she would tear the cervix and not be able to get pregnant again," White says. "She had a year off in between breedings, and when she was bred a second time, we did another cesarean section, again to prevent cervical injury. Both times she had normal foals. It was unlikely that the mare would have had more than one foal if we were to allow her to complete a natural birth."
While repeated C-sections can be performed, White states that the maximum number that can be safely done is unknown. "We don't know the limit," he says. "There are some concerns about conception. Most of the time after an elective cesarean section, the mare is able to conceive again, but there is a slightly lower rate of conception after this sur-gery."
Timing Is Everything
Timing the elective C-section is one of the most critical components to ensur-ing a safe delivery and a healthy foal. If the decision is made too late, the mare might go into a natural delivery with the resultant problems that caused veterinarian and owner to opt for a C-section in the first place. If the decision is made too early, the foal will be underdeveloped and suffer the consequences of premature birth.
"That's the critical issue: Is the foal ready to be delivered?" White says. "Because the gestation of the mare can vary from 11 months to well past 12 months, it can be difficult sometimes to make that distinction. The critical step is to monitor the mare daily to decide when she'll be ready."
Monitoring for signs of parturition or delivery begins about two weeks prior to the predicted delivery date. "A knowledgeable manager can probably learn many of the signs," says White, "but then as we get close to the delivery date, we look for other developments--milk production, relaxation of the vulva region, dilation (via a speculum exam of the cervix), and changes in the electrolytes in the milk." Normally the calcium content of mare's milk increases dramatically one to two days prior to the natural delivery date, and the sodium and potassium levels reverse whereby the potassium levels increase and the sodium levels drop.
When signs indicate the mare is about one to two days from delivery, she is sent to the veterinary hospital where the C-section will be performed. "The surgery needs to be done in a hospital environment," says White, "and for an optimal outcome these procedures should be done by specialists." Two veterinary teams are necessary--one to perform the actual surgery and the other to attend the foal while the surgeon completes the uterine and abdominal closure on the mare.
Prior to surgery, the mare undergoes general anesthesia and an incision is made through the midline of the abdomen. "The uterus is brought up and an incision is made through the uterus, usually over the body or one of the horns on its greater curvature," White explains. "Then we will find the rear limbs and pull the foal out through the incision. The umbilicus is clamped and cut. The mare has a very vascular (well supplied with blood vessels) uterus, so after the foal is removed, we take care to make sure the edges of the uterus are sutured to prevent excessive bleeding."
Absorbable sutures are used to close the abdominal and uterine walls, and staples are used in the skin. Surgery takes about an hour.
While the mare is being closed, other members of the staff work with the newborn, making sure the foal is breathing and dealing with any problems it might have. The foal is given colostrum from the mare or from a colostrum bank, or plasma might be administered as a source of antibodies if needed.
"Once the abdomen is closed, the mare is usually awake and standing within 30 to 60 minutes. Once the mare is back in the stall, the foal can start nursing as soon as it stands," says White. "The mare can have food one to two hours after returning to the stall. Antibiotics may or may not be administered after surgery; in healthy horses antibiotics are not necessary. We will usually give them oxytocin to stimulate the uterus to contract. If possible, the placenta is removed at the time of surgery; otherwise, we will treat the mare for possible infection in the uterus and monitor the uterus to make sure the placenta drops out normally and all of it is removed."
The foal is monitored to make sure it is healthy. "For the foal, this isn't really much different from a normal delivery, except he will be monitored more carefully in the first 72 hours. Foals are examined to make sure they have adequate gamma globulin (the antibodies that they absorb from colostrum), and to make sure they have no signs of anoxia (lack of oxygen to the brain), infection, or lung problems," notes White.
"If this is a healthy mare and foal, there's really not much else that we worry about except taking the mare's temperature daily to monitor for infection."
Generally, the mare and foal remain at the hospital for seven to 10 days, primarily to monitor the mare's abdominal incision and to watch for any complications. If all goes well, mare and foal are then sent home. After 12-14 days, a veterinarian should remove the staples and examine the abdominal incision and if necessary the mare's uterus. "They'll usually be in a stall with hand-walking for at least a month (because the abdominal incision is large)," White says. "Then they'll start a gradual increase in exercise, including turn-out over two or three months. This should be determined by a veterinarian. They're not really back to absolutely normal until two to three months after the surgery as far as the routine on the farm. But once the incision is healed, it won't take them any longer to get back to fitness than any other horse."
Prognosis And Risks
Usually, prognosis for the mare is excellent and that for the foal is very good. However, there are risks for both.
For the mare, as mentioned previously, conception rate could be a little lower due to the C-section. Additionally, because of the large, ventral midline incision that is made, there is some concern about healing of the incision and abdominal hernia formation. "But because it's an elective situation, that's not nearly the problem we might have in an emergency situation where there might be contamination or where the mare might be debilitated," White points out.
The major disadvantage for the foal is the possibility of incorrectly timing the delivery. "Timing is critical," White states. "Although we use several factors and monitoring to try to decide when it's proper to deliver the foal, they can have problems with prematurity or lung problems because of this method of delivery versus natural birth."
Another concern is side effects from the anesthesia, which the unborn foal receives from its mother when she is anesthetized for surgery. "When the foal is anesthetized, whether it's an elective or emergency cesarean section, they're going to be a little slow to wake up, but usually do very well," White says. "However, we are concerned because sometimes there is a lack of blood flow and oxygen into the foal from the placenta during the delivery phase and immediately after birth, so these foals can become anoxic suffering from a (lack of oxygen to the brain) and in 24 hours or so we may see signs of a 'dummy foal' where they've suffered brain damage. Nursing care in these foals can be critical until the problem resolves."
Finally, when delivery is completed in a hospital, there is always some risk of a nosocomial infection (one acquired at the hospital).
Although a natural delivery is always preferred for a mare and foal, the risks for delivery via an elective C-section are relatively low, and opting for such a procedure could mean the difference between a mare which can never become pregnant again and one which is able to produce foals a few more times.
About the Author
Marcia King is an award-winning freelance writer based in Ohio who specializes in equine, canine, and feline veterinary topics. She's schooled in hunt seat, dressage, and Western pleasure.