Initial examination
Since equine dystocia needs to be resolved rapidly, owners are generally advised to
seek assistance as soon as they suspect that parturition is not progressing normally,
e.g. the foal has not been born within 20-30 minutes of ‘the waters breaking’, a ‘red
bag’ (chorioallantois or prolapsed bladder) presents at the vulva instead of the
translucent white amnion, there are fewer (or more) than two hooves and a nose in
the vagina, or the mare has shown prolonged restlessness, discomfort or
unproductive straining. While waiting for veterinary assistance to arrive, it is often
useful for the client to walk the mare so that the foal drops back into the uterus; this
will help diminish straining and thereby reduce the severity of fetal hypoxia and the
risk of injury to the mare.
On arrival, the practitioner should take a brief history (e.g., previous foalings,
duration of gestation, recent illness, duration of labour) and perform a quick general
clinical examination of the mare, paying particular attention to possible signs of
haemorrhage, dehydration or shock (e.g. mucus membrane colour and capillary refill
time, pulse and respiratory rate and character), and general demeanour and/or state
of excitement. This is followed by an initial inspection of the perineal area for
evidence that parturition is in progress (presence of membranes or fetal parts at the
vulval opening), or of any other problems that may need to be addressed before
tackling the dystocia (e.g. vaginal trauma, haemorrhage, prolapsed rectum or
bladder). If there are any doubts that second stage labour is underway (e.g. the mare
was presented for prolonged restlessness, unproductive straining or colic), it is
sensible to begin with a per rectum examination to establish if parturition really has
started (e.g. a contracted uterus) and, if not, whether the foal is alive or whether
there is any other possible cause of abdominal discomfort; this further investigation
should be complimented by a more detailed history and clinical examination, e.g. gut
sounds, presence of colostrum in the udder (and if possible calcium/electrolyte
concentrations); on rare occasions, progression of foaling may be impeded by a
uterine torsion. If the mare is not in labour, a manual vaginal examination may not be
indicated and, in particular, the cervical canal should not be penetrated.
If the mare is foaling, she should be restrained appropriately and prepared for an
obstetrical examination by wrapping the tail and cleaning the perineum. Where
possible, sedation is initially avoided because most sedatives will cross the placenta
and depress the foal. However, if a twitch is not sufficient to allow proper and safe
examination, then se dation is a must. By preference, the obstetrical investigation
should be performed on the standing (even walking) mare, since this will encourage
the foal to sink back into the uterus, reduce the force of abdominal contractions and
make it easier to assess the disposition of the foal and the cause of dystocia. Mares
in labour can react unpredictably, and care should thus be taken that they do not
suddenly lie down or kick out.
Obstetrical examination
The aim of the initial obstetrical examination is to quickly assess the nature and
severity of any abnormalities, and formulate a plan for effecting rapid but safe
delivery of the foal. In the case of an apparent ‘red-bag’ delivery, once it has been
established that the protruding structure is the chorio-allantois (presence of the
cervical star, traceable back to the cervix) and not the bladder, it should be ruptured
or incised immediately. In this, as in other cases, the priorities are then to determine
Proceedings
of
the
South
African
Equine
Veterinary
Association
Congress
2016
242