Recto-Vaginal Fistulae
Introduction
A recto-vaginal fistula can be caused during foaling by the so-called foot-nape posture.
This occurs when the foal is presented with the legs forward without the head. The long limbs and relatively slender head of the foal make this posture feasible in the mare. The foot of the foal is directed dorsally by the transverse fold between vagina and vestibule. After a long period of severe non-productive straining, a foot-nape posture may lead to a rectovaginal fistula or eventually a third degree perineal laceration. In these cases both the dorsal vaginal wall and rectum are penetrated.
Recto-Vaginal fistulae can also be congenital.
Signalment
It is most common in primiparous mares. It is generally caused by a combination of poor alignment of the foal and excessive straining by the mare.
Treatment
If possible, it is important to keep the animal on her feet, and quiet walking may decrease straining efforts. Reposition is first attempted after epidural anaesthesia (which prevents straining). The foal is forcefully repelled and if possible the foreleg(s) are lifted and placed underneath the head. Lubricant and snares may be required to achieve this. If this is not successful and the foal is still alive, incision of the perineum may be necessary before extraction of the fetus. If the fetus is dead a quick partial fetotomy is indicated. The feet can be sectioned in the radius after which a careful extraction will be possible. The traumatised tissue should be checked for bleeding, and devitalised tissue removed. Final repair of the perineal laceration may be best delayed until weaning of the foal, i.e. at least a few months after parturition.
Prognosis
Although the function of the anal sphincter is not always completely restored, the prognosis for surgical restoration of the rectal and vaginal wall a few months after birth is good.
References
Endell Equine Hospital Foaling Information
Merck & Co (2009) The Merck Veterinary Manual (Ninth Edition), Merial
McGladdery, A (2001) Dystocia and post-partum complications in the mare In Practice 2001 23: 74-8
Pycock, JF (1997) Self-Assessment Colour Review Equine Reproduction and Stud Medicine Manson