In December, I was lucky to attend the 62nd Annual Convention of the American Association of Equine Practitioners in Orlando, Florida. The Annual Convention is one of the largest, if not THE largest, gatherings of equine veterinarians and technicians in the world, and it's a wonderful venue for all of us to get together and share the latest research and knowledge in equine veterinary medicine.
At the convention, I was able to attend a variety of informative lectures by some of the leading clinicians in their respective fields, and I would love to summarize some of these findings for our Badger Equine clients. The first lecture I will go over is “Review of How to Triage a Dystocia,” presented by Michael A. Spirito, DVM of Hagyard Equine Medical Institute, one of the largest equine hospitals in the country.
Dr. Spirito began his lecture by outlining what is considered normal during foaling, as an understanding of normal will help one to recognize when something is abnormal. Read about normal foaling in my blog post, Recognizing Problems In the Neonatal Foal.
According to a study performed by Frazer et al in 1997, the most common breeds to experience dystocia — or difficulty birthing to the point of human intervention — are Thoroughbreds, Standardbreds, and Draft breeds.
When a veterinarian is called for a dystocia, obtaining an accurate history of the patient is crucial to the initial decision making when it comes to handling the case. Some of the key questions that should be answered include:
- How old is the mare?
- Is this the first foal?
- Is the foal to term and has the mare bagged up?
- When did she begin to foal or break water?
- Have you seen or felt the foal move?
- Who owns the mare and are they aware of the situation? Will they want a C-section if required?
Having a complete and thorough history can help the doctor make decisions about the case prior to even examining the mare. Knowing what parts of the foal are visible to the owner can help the veterinarian determine the positioning of the foal inside the mare, and they can prepare for any manipulations that may be needed. Financial constraints of the owner may determine whether manipulation should be attempted on the farm or if immediate referral to a hospital is warranted. "Time is of the essence in dealing with a dystocia — 10 minutes can be the difference between an excellent result and a dead foal," says Dr. Spirito.
There are four procedures that can be used to relieve an equine dystocia. The first procedure is delivery of the foal via assisted vaginal delivery. Manipulation of the foal by the veterinarian can be performed while the mare is standing and sedated, and it can be performed both on the farm or at a referral hospital.
The attending veterinarian may use tools such as a head snare or chains on the legs to assist the mare in delivering the foal. Pulling on the chains is timed with the mare’s uterine contractions to reduce trauma on both the mare and foal. Once the foal’s shoulders are visible, the mare should be allowed to finish the delivery herself to prevent rib fractures.
Controlled vaginal delivery occurs when the mare is induced under general anesthesia and has her hind legs lifted via a hoist in what is called the "Trendelenburg position". This positioning is used to facilitate fetal manipulation by using gravity to help repel the foal further into the uterus, allowing more room to position body parts for delivery. Having the mare anesthetized also allows for manipulation of the foal without having to fight through the mare’s uterine contractions. This method is generally performed at a referral clinic, but it can be attempted on the farm for a short period if the proper equipment is available.
A Cesarean section, or C-section, is indicated when a foal cannot be delivered vaginally, such as in severely malpositioned fetuses, an abnormal birth canal, or in order to reduce reproductive tract trauma in a valuable mare. Unlike cattle, horses must be placed under general anesthesia on their backs in order to perform a C-section. This must be done at a referral hospital.
Despite a number of complications that can arise with surgery, mares that underwent C-section have an 80-85% discharge rate from the hospital, according to research done in 1999. Another study showed that 59% of mares that underwent C-section where able to have a live foal 1 year after surgery. The prognosis for future live foalings in years following a C-section was good if the duration of dystocia was less than 90 minutes prior to surgery and if the mare was younger than 16 years old at the time of surgery.
Fetotomy, or sectioning of the fetus, is reserved for dystocia when the foal is confirmed dead and vaginal manipulation does not result in successful delivery. Due to potential complications, fetotomy should only be done by experienced personnel. (Dr. Kiser has performed several fetotomies both during her internship/residency and while in private practice.)
Before fetotomy is performed, one should have a plan and the sections should be removed at precise anatomic locations. "If fetotomy is performed in a judicious, cautious matter, then the mare will have a productive life. If not, she may be significantly damaged," says Dr. Spirito.
Dr. Spirito then outlined some of the most common fetal presentations that can cause dystocia, the manipulations that can be used to reduce the malpositioning, and how to progress if the foal is alive or how to section the fetus properly if it is dead.
This video outlines some common presentations requiring intervention or C-section:
In Dr. Spirito’s experience, there are instances when C-sections are performed as an elective procedure, usually if the mare has a pre-existing condition such as a damaged cervix or deformed/damaged pelvis. There are also several fetal presentations for which manipulations should not be attempted and which should go directly to C-section. This includes breech and transverse presentations. If a Cesarean section cannot be performed for any reason, the veterinarian may attempt vaginal delivery or fetotomy in the field. If the foal is valuable, perform a C-section.
"It is important not to linger with uncertainty in dealing with these problems," says Dr. Spirito. "It is very easy to spend 15-20 minutes trying to reduce a dystocia, and this is valuable time for several reasons: the obvious one is the viability of the fetus, but also fatigue and swelling of the birth canal in the mare should be considered. … We make a point to try and determine early in the process whether a C-section is going to be required."
In summary, dystocia in the horse is a very time-sensitive emergency that must be recognized and treated quickly. Keeping a cautious eye on your mare if she is expecting and calling an equine veterinarian at the first sign of trouble could be the difference between a good or tragic outcome.
Contact Dr. Allison Kiser of Badger Equine Veterinary Services with your foaling questions and concerns.