POST FOALING EMERGENCIES IN THE MARE
Tom A.E. Stout.
Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University,
Utrecht, The Netherlands
Introduction
Reproductive emergencies are relatively uncommon in the mare, but the vast
majority of those that do occur arise during late gestation, at foaling or in the
immediate post-partum period. In all cases, establishing a (presumptive) diagnosis is
important because symptoms are often non-specific whereas failure to rapidly
address the problem or initiate adequate s upportive therapy can significantly worsen
the prognosis. This lecture will concentrate on the diagnosis, treatment and/or
management of post-partum conditions that involve the reproductive tract and
require treatment as potential emergencies. It is important to consider that not all
post-partum crises are caused by abnormalities of the reproductive tract, but that
damage to or displacement of other abdominal, particularly gastro-intestinal, or pelvic
structures are important differential diagnoses; indeed, the clinical signs are often
similar whereas the therapeutic approach may be very different.
Of the potential post-partum complications affecting the reproductive tract, retained
fetal membranes and acute septic metritis are the most commonly encountered,
while uterine prolapse or inversion (invagination) of a uterine horn, uterine tears, and
severe reproductive tract haemorrhage or trauma are less common but important to
recognize because early correction can significantly improve the prognosis.
Retention of the fetal membranes / acute septic metritis
Retention of the fetal membranes (retained placenta; RP) and/or acute post-partum
metritis are the most common post-partum problems encountered in equine practice.
Although RP is not an acute emergency in the first instance, if it is not dealt with
promptly and adequately, it can become so as a result of rapid progression into an
acute septic metritis with the potential to cause septicaemia or endotoxaemia which
can, in turn, result in laminitis and/or death.
The fetal membranes are normally passed within about 1 hour of foaling, and RP is
therefore generally defined as failure of the membranes to be passed within 3 hours
(Sevinga et al., 2004). The incidence of RP in the general equine population is
around 2-10%, but it is considerably more frequent in Friesian horses (54%; Sevinga
et al., 2004) or following dystocia, induced parturition or caesarean section. Often,
the fetal membranes that remain most firmly attached are those in the tip of the nonpregnant horn. The major issue of failure to pass the entire fetal membranes
promptly is that the devitalised material provides a perfect medium for bacterial
proliferation, a process that accelerates from around 6-8 hours after parturition.
In the case of a promptly diagnosed RP (3-4 hours post-partum), the aim of the
clinician is to prevent the development of acute metritis by encouraging timely
passage of the membranes. The most common initial approach is treatment with
bolus injections of 10-20 i.u. oxytocin from 3 hours after foaling and, if necessary,
repeated 2 hours later. Some practitioners favour using the ‘Burns technique’ of
distending the chorioallantoic sac with 12-15 L of clean water or dilute povidone
Proceedings
of
the
South
African
Equine
Veterinary
Association
Congress
2016
246