There are many reasons why a mare may need surgical help delivering her foal.

In situations where a mare can’t deliver her foal, the only way to save the mare—and possibly the foal—may be to take the foal out surgically.

Margaret Mudge, VMD, assistant professor of equine emergency and critical care at Ohio State University, said that mares have a very short labor.

“This is quite different from most other species. Labor in the mare is very brief and explosive,” she said.

If the mare has a dystocia, there’s only a short window of time in which this can be safely corrected and still result in a live foal. After that, it becomes a matter of just trying to save the mare.

Cesarean sections fall into two categories: elective surgery and emergency surgery. Most are emergencies in which the mare has a dystocia, and the foal cannot be delivered vaginally. The only options left are a fetotomy (removing a dead foal through the birth canal in pieces) or a C-section.

Choosing A C-Section

If the mare has a known pre-existing condition, an elective C-section might be scheduled. Mare owners should be aware of any abnormalities, which are usually discovered during a breeding soundness exam.

Pelvic abnormalities are one example—such as a previous fracture that healed but left the pelvic area altered—or a tumor mass like melanoma growths in the pelvic area, or excessive scarring.

A mare might have a recto-vaginal tear from a previous foaling that was repaired but left the birth canal very narrow, or she might have a cervical injury. The owner might be lucky enough to get her in foal again but not want the risk of re-tearing a cervical laceration during another foaling. A cervical injury would reduce the mare’s chances of getting in foal again.

If there is any marked limitation in the size of the pelvic canal, this might require a C-section delivery of the foal. In these instances the mare owner needs to be working closely with a veterinarian to monitor the readiness of the mare for foaling. The foal has a much better chance of survival if the mare is actually in labor at the time of the surgery.

“The mare will have a good prognosis, no matter what, with an elective C-section. The foal, however, will have a much better prognosis if she has either started early labor—which would be ideal—or is at least very ready, and labor can then be induced,” said Mudge.

A mare’s readiness can be tracked by checking the milk electrolytes and watching the changes.

“Several reports indicate that if done properly, we can get up to 90 percent foal survival with elective C-sections, in the right circumstances. This does not include surgeries in mares that are acutely colicky and the owner feels we should take the foal out because she’s near term. Success rates are not as high when the foal is taken too early,” said Mudge.

“This is very frustrating for us and difficult for owners to understand,” she added. “Just because the mare, in number of days of gestation, is near term, the foal may not be ready.”

Fetal maturation and readiness increases considerably when the mare is ready to start labor, during the last days or hours of gestation. To take the foal out even a few days ahead of this time period threatens his ability to survive outside the uterus. Foals are not as likely to survive as are premature human babies or calves taken out of the uterus prematurely.

Mudge recalled one mare who required colic surgery to remove enteroliths two weeks before her due date.

“The temptation for an owner in this situation is to go ahead and take the foal out, to relieve stress on the mare,” she said. “But an enterolith surgery in most horses has a very good prognosis, and in this mare we closed her back up, and seven days later she foaled, with a very healthy foal. The outcome for the foal wouldn’t have been good if we’d taken it out at the time of the colic surgery.”

Mares rarely foal right on their due dates; they often foal two or three weeks earlier or later. They have a wide variation in gestation lengths, from 320 to 360 days. It is more appropriate to determine the end of a pregnancy by fetal readiness rather than an arbitrary due date.

When It’s An Emergency

“If the mare must have an emergency C-section, owners need to have the proper expectation,” said Mudge. “Sometimes they bring a mare here saying they want us to save the foal—that the foal is most important to them—but this may be impossible. They need to re-prioritize. In most cases, to us, the mare is the most important because all we can actually do is try to save her.”

There are occasional cases in which the mare has a terminal condition such as severe colic or another serious disease in which it’s a terminal C-section to save the foal because the mare will be put down following surgery.

“Even in those cases, the foal doesn’t have as good a chance as in situations with an elective C-section,” explained Mudge.

She sees emergency C-sections far more frequently than elective C-sections. “We have a very wide referral radius, so it’s not unusual for mares with dystocia to be referred to us from three hours or more away. Clearly, this sets it up for a very poor survival rate for the foals,” she said. “Reported foal survival rates for dystocias seen at referral hospitals range from 5 to 30 percent.”

Survival rates for mares, on the other hand, are approximately 90 percent.

“When the foal is dead, there are other options in addition to assisted or controlled vaginal delivery, including fetotomy, though there are certainly cases in which we decide that a C-section would be the least traumatic to the mare and to the health of her cervix,” Mudge said.

This is especially true when it has been several hours since a mare began her labor. The longer it’s been, the more compromised the uterus could be.

“In these cases we are not doing a C-section to save the foal. We are doing it to save the mare and her future reproductive capabilities,” said Mudge.

The Usual Procedure

When a mare arrives at the clinic, she is quickly checked to see if the foal can be delivered vaginally or if she must be taken to surgery.

“Most facilities like ours are quite successful in delivering foals through controlled vaginal delivery, under anesthesia, because the mare is unable to strain,” Mudge said. “We hoist up her hind end and gravity helps us. The foal has dropped away from her pelvis and she’s not straining, and this makes it easier for our
manipulations.”

Everything goes at high speed if there is a live foal involved. After a quick evaluation of the mare, if the foal is not deemed able to come out via assisted vaginal delivery (a decision that is made within a few minutes), the mare is then anesthetized in order to attempt a controlled vaginal delivery.

“If the foal is alive, we don’t give ourselves very much time at this—no more than 15 or 20 minutes. If our efforts aren’t successful within that time, the mare goes straight to surgery,” said Mudge.

The mare is already anesthetized, which saves time. Also, while one person is doing the manipulation to try to deliver the foal, another person is clipping the mare’s belly and prepping her for surgery, to save more time.

Someone always has to time the person doing the manipulations. “We can easily become so focused on trying to manipulate the foal that we lose track of time. It’s a very important job to time all this and have someone telling us when time is up, and we need to quickly move the mare to the surgery room,” she said.

By then the time it takes to do the final prep on her belly and for the surgeon to scrub is very brief.

“Any time there’s even a remote chance of getting a live foal we have the entire medicine and neonatal team here to work on the foal,” said Mudge. “Sometimes the foal isn’t alive by the time it’s delivered surgically, but we always have everything in readiness. Having that second team ready to resuscitate the foal is crucial.”

This is quite different from a difficult delivery in cows, since calves are more likely to make it a precarious birth without as much intensive care.

Aftercare And Recovery

The aftercare for the mare is similar to that of a colic surgery, on the ventral midline of the belly, though with a longer incision.

Because of this long incision, the mare’s exercise must be limited during the first part of her recovery, to give the tissues a chance to heal.

“We recommend keeping her in a stall for the first month. Then she can have a little bit of turnout during the second month. The time frame on these recommendations will vary a little bit from surgeon to surgeon, but it mainly has to do with how quickly the body wall heals. By the third month the mare can usually have free turnout,” Mudge said.

Keeping the mare confined can be an issue, however, if you are lucky enough to get a live foal after the surgery. This becomes a management challenge, because the foal needs exercise. Most people take the mare and foal out of the stall daily and keep her on a lead, hand walking her in a paddock while the foal can frolic around her.

Future Fertility

The aftercare for the mare will include antibiotics and anti-inflammatory medication to help reduce the effects of shock. She will also be given oxytocin to help her shed the placenta.

Depending on how quickly the mare sheds her placenta and how quickly her uterus involutes, she may or may not rebreed that season; it also depends on how early in the year she had the surgery and how well she recovered.

“One study, reported in 2003 in the Equine Veterinary Journal, showed a very good foaling rate of 60 percent in the year following a C-section,” said Mudge.

“Mares can be fertile after a C-section but are probably less so than the average mare that season. If the mare had a C-section in May, for instance, it is less likely that she would breed back again that year. It might take her until next year to be fully ready to breed again, and the owner is better off just waiting. If she had a C-section in January or February, however, there might be more chance of getting her rebred that season,” explained Mudge.

The traumatic nature of the situation may be a deterrent, emotionally, for the owner.

“Labor in the mare is explosive, and if something goes wrong it can be very stressful to both the mare and the owner. For the inexperienced owner with a pleasure horse or show mare, this can be very traumatic, and they may decide they don’t want to risk going through this again,” she said.

Owners may wonder if a mare who has had a surgical delivery will now require a C-section with future foals, because this is the mantra in many human hospitals, that once a woman has had a C-section she must always have a C-section.

“This is not the case in horses. It’s generally a mal-positioning of the foal or a limb retained which created the need for C-section. It’s usually not the fault of the mare, unless it’s a situation where she has a pelvic obstruction like an old fracture. If it’s due to something anatomic in the mare, then yes, she’d need a C-section for every foal, and she might not be your ideal broodmare. But if the problem is due to mal-positioning of the foal, there’s no reason she’d need a C-section the next time,” said Mudge.

The chances of having a similar dystocia in the future would be low.

“We’d look at these mares as potential high risk and would want to monitor their future foalings very carefully,” said Mudge, “but they generally go ahead and have normal subsequent foalings.”

If you enjoyed this article and would like to read more like it, consider subscribing. “Surviving A C-Section With Your Mare” ran in the February 12, 2010  issue. Check out the table of contents to see what great stories are in the magazine this week.