Uterine torsion
Keywords: uterus, equine, torsion, pregnant
Uterine torsion should be suspected in any mare that is pregnant, in advanced gestation and is presented with colic. Torsion is usually easy to diagnose because the mesometrial ligament is pulled tightly to one side and in most cases, is clearly palpable per rectum.
Image size: 1384 x 643px
This author and holder of copyright of this image is Dr G.F Richardson. (grichardson@upei.ca).
The basic principle for non-surgical correction of uterine torsion in mares is to introduce general anesthesia and to "roll the dam around her uterus" leaving her uterus behind (!) The same philosophy is applied in cows except that general anesthesia is not required.
A plank such as that shown at left in the inset can be used to stabilize the uterus while the mare is rotated on her longitudinal axis. In an effort to stabilize the uterus while the mares is rotated, pressure can be placed on the plank. As shown below, one may even wish to stand on the plank for additional pressure. Some have argued that the use of a plank is not essential to correct uterine torsion. This author suggests that its use is logical and potentially valuable.
Image size: 784 x 523px Copyright of Dr J Dascanio. LMU College of Veterinary Medicine john.dascanio@lmunet.edu
Transrectal examination after rolling will usually reveal if the torsion has been corrected. If an initial attempt fails, rolling should be repeated. When rolling fails altogether, the mare is recovered and a standing flank laparotomy is often used to correction of the torsion. However, a fairly recent paper by Jung et al, suggests that ventral laparotomy should be attempted in all cases, in preference to rolling.
Occasionally the foal dies as a result of blood vascular embarrassment and is aborted soon after the torsion is corrected.
Notes:
The survival rate of foals is greater when torsion occurs earlier rather than later in gestation. This is probably because of tension on blood vessels, the possibility of uterine or mesometrial rupture and greater difficulty in correcting torsion due to its sheer weight in later gestation.
In rare cases, crossed and tense mesometrial ligaments cannot be palpated per rectum. It is not clear why this is the case but it does serve to remind one that torsion cannot be discounted if the history still points to uterine torsion. Apparently, torsion can be determined by palpation of the body of the uterus in those cases.
Reference:
Chaney, K.P. et al. 2006 Effect of Uterine Torsion on Mare and Foal Survival: A Retrospective Study 1985–2005 Proc. AAEP 52:402-403
Doyle, A. J. et al. 2002. Clinical signs and treatment of chronic uterine torsion in two mares J. Am Vet. Med. Assoc. 220:349-353
Jung, C et al. 2008. Surgical treatment of uterine torsion using a ventral midline laparotomy in 19 mares. Australian Vet.J. 86: 272-276
