Uterine torsion

Keywords: uterus, equine, torsion, pregnant

Uterine torsion is a problem that generally occurs in the last half of gestation in mares.  This is very different to cows, where torsion is occurs during calving. Generally therefore, no consideration is given to delivering the foal after torsion is relieved; it would usually be too immature to survive.

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.

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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

Congenital testicle torsion

Keywords: torsion, testicle, stallion, equine

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A 4 year old Paint stallion with 180 degrees (estimated) torsion of the right testicle; the tail of the epididymus was lying within the cranial aspect of the scrotum. A bulge caused by the tail of the epididymis is indicated by a red arrow. This was discovered during a routine breeding soundness evaluation.

As mentioned in another LORI entry on testicular torsion, it should in theory, be almost impossible because the mesorchium is usually a short and tight ligament between the parietal and visceral vaginal tunics, running the entire length of the dorsal aspect of the testicle. In this case, torsion was probably the result of congenital malformation; congenital malformations are known to predispose humans to testicular torsion.

This stallion was fertile and did not experience any pain from the condition.

Reference:

Wyatt J. K. and Mundy  H. B. 1972  Torsion of the testicle: a clinical review of 20 cases, Can Med Assoc J. 107: 971–973

Testicular torsion with hydrocele

Keywords: testicle, torsion, hydrocele, equine

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Caudal view of a three year old Standardbred stallion presented for castration after discomfort during exercise. Examination revealed a right-sided hydrocele (fluid accumulation in the vaginal cavity surrounding the testicle). Testicle torsion was ascertained by palpation and ultrasound (inset) and confirmed during surgery. Bilateral castration was performed.

It is not clear how testicular torsion develops in stallions because the mesorchium is usually a short ligament between the parietal and visceral vaginal tunics, running the entire length of the dorsal aspect of the testicle (the testicle is suspended horizontally in equids).  Therefore testicular torsion should in theory, be almost impossible. It does however, occur. Perhaps the mesorchium may stretch under some circumstances (such as hydrocele in this case) allowing the testicle to rotate horizontally on its dorsoventral, transverse axis. This has certainly be shown to be the case in humans, where testicular torsion in not rare.

The question remains: In this case, was the hydrocele a primary condition, allowing torsion in this case or was it secondary to the torsion? There was neither overt strangulation nor vascular embarrassment of the spermatic cord; not enough to cause tissue necrosis but perhaps enough to cause hydrocele.

In some cases testicle torsion appears to be partial, congenital and is innocuous, causing neither infertility nor vascular embarrassment.

Reference:

Wyatt J. K. and Mundy  H. B. 1972  Torsion of the testicle: a clinical review of 20 cases, Can Med Assoc J. 107: 971–973