REPRODUCTIVE EMERGENCIES IN LATE
GESTATION
Tom A.E. Stout
Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, the Netherlands
Introduction
Late gestation reproductive emergencies are relatively uncommon in the mare.
Nevertheless, rapidly establishing a (presumptive) diagnosis is essential because
symptoms are often non-specific whereas failure to rapidly address the problem or
initiate adequate supportive therapy can significantly worsen the prognosis. This
presentation will concentrate on the diagnosis, treatment and/or management of late
gestation conditions that involve the reproductive tract and require treatment as
potential emergencies. While they will not be discussed, it is important to include
damage to or displacement of other abdominal or pelvic structures among the
differential diagnoses, since the clinical signs may be similar while the therapeutic
approach is likely to be different. Late gestation reproductive emergencies that can
be life-threatening to the mare include uterine torsion, abdominal wall or pre-pubic
tendon rupture and rupture of a uterine (or other reproductive tract) artery. Other
conditions that require prompt attention but more specifically affect and endanger the
fetus such as imminent abortion, hydrops of the fetal membranes, placentitis and
other causes of (threatened) abortion will not be addressed in this presentation.
Uterine torsion
Uterine torsion can arise anytime between 5 months of gestation and term, but is
most commonly seen at 8-9 months. Uterine torsion involves the rotation of the fetus
and uterus by more than 180o, beyond which self-correction is very unlikely. Affected
mares generally present with mild but persistent colic (e.g. pulse rate 60-80), that
initially responds to analgesia. In a mare close to foaling, the discomfort of uterine
torsion can thus easily be confused with first stage labour.
Irrespective of the stage of gestation, diagnosis of uterine torsion depends on per
rectum palpation of one broad ligament passing over the other; presence of a single
taught ligament running across the abdomen is not sufficient for a definitive
diagnosis since it could represent a ‘physiological rotation’ that can self-correct. The
relative position of the crossed broad ligaments indicates the direction of the torsion;
e.g. in the case of a torsion to the left (anti-clockwise) the left ligament will be
positioned caudally to the right ligament, and vice versa for a clockwise torsion.
Confirmation of the diagnosis can be assisted by establishing that fetal parts are
palpable only cranial to the crossed broad ligaments; on some occasions, the vagina
may also be twisted in the direction of the torsion (Spoormakers et al, 2015).
The treatment of choice for uterine torsion depends on the stage of gestation; if signs
of fetal readiness for birth are present, per vaginam correction and delivery of the
foal or caesarean section are indicated. Earlier in pregnancy, the preferred approach
is manual correction via a standing flank laparotomy since it offers better fetal
survival than the alternatives, probably because it does not involve general
anaesthesia unlike ‘rolling’ the mare or mid-line laparotomy. The post-correction
prognosis for both mare and foal depends on the stage of gestation at occurrence,
Proceedings
of
the
South
African
Equine
Veterinary
Association
Congress
2016
238