Equine dystocia
Keywords: equine, foaling, dystociaIn most cases of the equine dystocia, the foal dies quickly. In fact, the vast majority of foals involved in dystocia will be dead by the time the veterinarian arrives. This is because the equine placenta separates from the endometrium rapidly during foaling. This is distinctly different to the situation in cows where the majority of calves are still alive when mutation and traction are first attempted.
Epidural anesthesia is slow and unpredictable in mares and therefore of limited value in cases of dystocia. However, it can be used for fetotomy in standing restraint (when the fetus has died) because there is usually time to perform an epidural and wait for it to take effect. In fact, epidural anesthesia was used to relieve dystocia by fetotomy in the inset of the main image below. If an attempt at epidural anesthesia fails, it is useful to remember that brief periods of relief from straining can be obtained by pulling out the tongue of the mare. This makes it impossible for her to close her glottis and strain during attempts at mutation and traction.
Because sympathetic stimulation causes uterine relaxation, the beta 2 sympathetic agonist clenbuterol is an excellent tocolytic and should be used when possible. However, it may not be used in countries where horse meat is used for human consumption. The use of clenbuterol may be banned in cattle for that reason as well.
Image size 1650 x 946 px.
If a live foal cannot be delivered in 5 to 10 minutes, general anesthesia should be induced immediately. This provides restraint as well as excellent uterine relaxation. When the hind quarters are elevated, the foal also moves cranially providing space in the uterus for fetal mutation. Under farm conditions, the author is aware of dystocia that was relieved by raising the hind quarters of an anesthetized mare using a tractor with a front-end loader!
Under more sophisticated conditions, such as a hospital adjacent to a major breeding facility, an attempt at mutation and traction is made while the mare is prepared for a potential cesarean section. This saves time in the event that a cesarean section is required.
3264 x 2448 px. Image copyright of Dr R.M. Embertson. rembertson@roodandriddle.com
If delivery is not successful while the mare is being prepared for surgery (~ 10 to 15 minutes) one can immediately resort of surgery. In this manner, the majority of foals will be delivered live. Under field conditions, most will die before or during mutation and traction.
