British Breeder Magazine May 2021

The best approach to managing a
foaling mare is to watch her very closely
but without disturbing her. Having an
experienced attendant watching the
mare and assisting if necessary is the
best way of reducing the risk of problems
at foaling. However, mares vary
tremendously in the signs of impending
foaling that they actually show, hence it
is possible to waste much time waiting
for a mare to foal. To avoid this, options
include:
(1) Measuring the electrolyte
concentrations in prefoaling udder
secretions using kits that are available
commercially. These kits measure
electrolyte levels in a sample of udder
secretion. When the amount of calcium in
the milk increases above a certain level,
over 95% of mares will foal within 72h.
(2) Foaling alarm systems, such as a
small transmitter lightly stitched to the
mare’s vulva. When she pushes the
fetal membranes through the vulva
at the beginning of foaling, a pin in
the transmitter is pushed out. This then
sets an alarm off, which activates the
attendant’s pager. The disadvantage is
that the alarm only alerts you once the
mare starts to deliver, so you need to be
nearby.
(3) Foaling alarm systems that strap
around the whole mare and sound an
alarm if or when she sweats during
delivery. The disadvantage of this is that
if the mare does not sweat it does not go
off. Closed-circuit TV is also commonly
used. Because parturition is very rapid
in mares, it is important to monitor them
very closely.
Nursing/management checks
before foaling - It is important to
check if the vulva has been stitched
(Caslick’s operation). If she has been
‘stitched’ it is important to ‘open’ the
vulva before foaling. It is not enough
just to remove the stitches that were put
in when the mare was ‘Caslicked’, and
in any case these should have been
removed 2 weeks after the procedure.
The stitched area must be cut open
before the foal emerges. If this is not
done, at best the tissue of that area will
tear and bruise severely, making future
repair difficult; at worst, the foal will
suffocate. It is also an important hygiene
measure to wash and dry the mare’s
udder.
Parturition
Parturition is the term used to describe
the expul-sion of the fetus (and its
membranes) from the uterus through the
maternal passages by natural forces.
The most important initiating factor for
parturition is the maturation of the fetal
hypothalamic–pituitary–adrenal axis.
The production of cortisol from the fetal
adrenal gland may be the ultimate
trigger of the process of parturition.
This increase in cortisol indicates the
foal’s ‘readiness for birth’. Oxytocin is
the hormone produced by the dam and
plays a key role in all stages of labour.
In the mare oxytocin release can be
blocked by external stimuli, which allows
the mare, at least temporarily, to resist
the fetal signals for birth, e.g. if she is
disturbed. The act of parturition is a
continuous process but it is customary
to divide it into three stages, as in other
species.
First Stage - This lasts for 1–4h
and begins with the onset of uterine
contractions. The changes are not visible
externally but they prepare the birth
canal and fetus for expulsion. During this
stage the muscles of the uterus begin to
contract and push the fetus against the
cervix. This helps the cervix to dilate. The
foal begins to move of its own accord,
rotating itself and extending the front legs
and head. The increasing myometrial
activity, together with spontaneous fetal
movements, will result in rotation of the
cranial part of the fetal body into a
dorsosacral position. The front legs and
head are extended. These processes
usually result in discomfort in the mare
and the following signs:
• Becoming restless and exhibiting
colic-like signs (looking at flanks, tail
switching, frequently getting up and
down).
• Exhibiting patchy sweating (flanks,
neck, behind elbows).
• Yawning.
• When the cervix is fully dilated
the allantoic membrane ruptures
and several litres of allantoic fluid
escape from the genital tract. This
is popularly called ‘the waters
breaking’ and indicates the end of
the first stage.
As the mare approaches the end of the
first stage of labour her tail should be
bandaged and her vulval area cleaned
and dried. Mares do not normally strain
during the first stage of parturition.
Second Stage - The onset of the
second stage occurs abruptly and
commences with the onset of forcible
abdominal straining and/or the
appearance of the amnion. These
two features usually occur almost
Features - Foaling the Mare
simultaneously. During stage two, actual
delivery of the foal takes place. The
mare usually lies down and goes into
lateral recumbency until the foal is born.
The outer red membrane ruptures and
the amnion (transparent bluish-white
membrane) is quickly visible at the vulva
and fluid and a fetal foot should be
visible. Straining occurs regularly and
both front feet should soon appear. As
the amnion emerges at the vulva, one
foreleg is in front of the other by some
10cm. Shortly the nose should appear
also. The greatest effort is associated
with delivering the head, with the
passage of the chest and hips usually
occurring relatively easily. As the head
and shoulders pass through the pelvis,
the amnion should rupture. If necessary,
the mare can be assisted by gentle
pulling on the foal’s front legs.
The foal has a relatively long umbilical
cord, which is still intact after delivery.
When possible, the cord should be
left intact for a few minutes to help
the circulation of the newborn foal.
Care should be taken not to disturb
the mare at this stage or she may rise
and rupture the cord. The cord usually
ruptures at a predetermined place
due to movements of the mare and/
or foal several minutes (up to 15min)
after birth. Once the umbilical cord has
ruptured, the stump should be checked
for haemorrhage and disinfected with
dilute chlorhexidine. This disinfection of
the navel needs to be repeated several
times during the first few days of life. If
the mare is still lying down, the foal can
be moved towards the mare’s head to try
to reduce the chance of the foal being
stood on when the mare attempts to get
up. All disturbances should be kept to a
minimum during this stage. The second
stage of labour usually occurs at night;
the average duration is about 15min and
normally it should not exceed 1h.
Third stage - This involves passage
of the fetal membranes, often termed
‘delivery of the afterbirth’, and
usually occurs within 1h on average
and should not take more than 2h.
Continuing myometrial activity plays
an important role during this process.
There is controversy with respect to the
time interval for placental expulsion.
Recognition of the precise time at which
the process has become pathological if
the membranes have not been passed
is difficult.The placenta initially should
be tied up so that it hangs just above
the hocks. This should avoid it being
stepped on before it is passed. If the
placenta is not passed within 3h, the vet
should be contacted. The uterus contracts
very quickly after foaling and this
process carries on for several days until
the uterus is almost as small as it was
before the mare became pregnant. This
process of becoming smaller is known as
‘involution’.
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