Management Of Dystocia

By | 2012-10-25

Materials required to correct a foaling problem may be as simple as an obstetrical sleeve, lubricant, and some baling twine. However it is common practice for a clinician to have on hand a pair of obstetrical chains (or straps) and handles or a Krey-Schotter hook, and a snare rod. Copious lubrication is often the key to success. A fetotome, wire, handles, guide, and a guarded scalpel are necessary to perform a fetotomy. Cleanliness is essential as is a large working area with good footing. The behavior of a foaling mare can be unpredictable and violent, thus safety for all personnel is an important consideration. Ideally the obstetrician should have access to a hospital facility where general anesthesia can be given and an overhead hoist system is available to lift the mare’s hindquarters.

The degree of restraint required for a safe examination and fetal extraction will vary with the individual mare. Although placement of a large-bore stomach tube or endotracheal tube into the mare’s trachea is reported to reduce straining, this procedure is of little benefit clinically. Application of a nose twitch or other methods of physical restraint offer limited help. Epidural anesthesia will reduce straining in the standing mare but the time needed to obtain an effective block precludes its routine use. Certainly the hindlimb ataxia that can be associated with an epidural is contraindicated if general anesthesia becomes necessary. Short-term xylazine-ketamine general anesthesia may not eliminate straining but will often permit positioning of the mare to facilitate manipulation of the fetus. Inhalation anesthesia will relax the mare and eliminate straining. Clinicians should be cautious about eliminating uterine contractions because they are beneficial to the delivery process after postural abnormalities of the fetus have been corrected.

Often there is insufficient space within the pelvic canal to permit correction of even simple fetal malpostures; thus repulsion of the fetus from the maternal pelvis back into the uterus is usually an integral part of dystocia correction. The degree of uterine contraction will influence the success of this procedure. Distention of the uterus with liquid obstetric lubricant often provides the extra space needed. If the mare is straining excessively, and/or the uterus is tightly contracted, administration of general anesthesia and elevation of the hindquarters is indicated. This method will reduce the amount of intraabdominal pressure on the uterus and permit the fetus to fall away from the pelvic canal. Elevation of the mare’s hindquarters allows the obstetrician to work at a more comfortable level and also eliminates the increased abdominal pressure that occurs if the mare is in lateral recumbency.

Because the value of a foaling mare may range from minimal to millions of dollars, it is impossible to be dogmatic about management of an obstetrical case. The economics of each case will play an important part in the decision process as the clinician contemplates the options — fetotomy, cesarean section, manipulation, and vaginal delivery. The breeding future of the mare must be considered because trauma to the genital tract will have an adverse effect on future fertility. Liberal application of lubricant is essential to protect the delicate membranes. Prolonged vaginal intervention is contraindicated in mares, because the cervix is easily traumatized. Slow traction while monitoring cervical stretching is recommended. If the mare is not under general anesthesia it is best to coordinate traction with the mare’s expulsive efforts.