Page 488 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Reproductive system: 2.1 The female reproductive tr act 463

VetBooks.ir • Perineal melanomas. This condition can Surgical technique and
complications
make life painful for the mare. Use of low-dose
sedation or epidural anaesthesia should improve
under general anaesthesia, in dorsal recumbency,
the situation. but it is better to address this In general, most surgeons perform this operation
before putting the mare into foal it possible. and via a mid-line ventral laparotomy extending
from slightly caudal to the umbilicus and cranially
CAESAREAN SECTION for 50–60 cm. Occasionally, a paramedian approach
is used if there has been previous midline surgery
Indications or injury. The most common surgical complication
Caesarean section is indicated when delivery of the is severe postoperative uterine haemorrhage from
foal is not possible per vagina (e.g. grossly oversized the uterine incision. The incidence of this can be
foal; severe fetal malposition that cannot be easily decreased considerably by careful positioning of the
rectified such as ‘dog sitter’; transverse presentation; initial incision, clamping and ligating the larger ves-
and severe congenital deformities). Problems of the sels, applying a specific haemostatic suture if consid-
mare that may lead to a decision for a caesarean sec- ered necessary, and the use of oxytocin in the latter
tion include: previous pelvic injuries; tumours of the part of the operation and postoperatively. Mares
vaginal canal or perineum such as melanoma; pre- require very careful monitoring after the operation
vious perineal injuries that have not been treated in order to identify and deal with other complications
correctly or have scarred excessively; ruptured pre- (e.g. retained placenta; abdominal incision problems
pubic tendon injuries; ventral abdominal hernias; and such as local infections and breakdown; laminitis/
uterine torsion. In order to obtain a live foal, surgery metritis, particularly in draught breeds; shock; peri-
needs to be carried out as soon as possible and usu- tonitis; and, in the longer term, adhesions). Usually
ally within 1 hour of the start of the second stage of the mare is not bred until the next breeding sea-
parturition. The procedure requires a general anaes- son and free exercise is usually limited for the first
thetic, a sterile operating environment and a trained 3 months postoperatively. Many foals are delivered
surgical team, which may not be readily available in dead at caesarean section and any that are alive are
some areas and which certainly leads to significant high risk and need appropriate intensive care. Mare
costs to owners. Postoperatively, the mare will have and foal should be reunited as soon as possible
lowered, but still acceptable, fertility rates. because bonding between the two can be a problem.

THE POST-PARTUM PERIOD

Mares usually recover within an hour of foaling, Mares that have had a difficult parturition, especially
returning to normal behaviour (i.e. looking after those where manipulations were required or whose
their foal, eating, drinking, defecating and urinat- post-partum management and exercise were compro-
ing). During this time pulse and respiratory rates mised, may require additional time and/or treatment
return to normal and mucous membranes resume to allow resolution of any infection or inflammation
their normal pink colour. and complete involution to occur.
Under the changing hormonal balance in the
post-partum mare, uterine contractability increases FOAL HEAT
and fluid, bacterial contamination and cellular debris
are expelled from the uterus. Immune reactions are Shortly after foaling the ovaries of the mare start
stimulated in the uterus and assist in dealing with any to become active and follicles develop and ovulate
post-partum bacterial contamination. Uterine involu- between 5 and 15 days post partum. This is asso-
tion occurs within 6–15 days post partum, with a rapid ciated with oestrus signs or ‘foal heat’, usually
decrease in uterine size back to normal by 30 days. 6–12 days post partum. The length of the foal heat,