Page 504 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Reproductive system: 2.1 The female reproductive tr act 479

VetBooks.ir be dealt with urgently. External sutures are removed 2.85
10–14 days postoperatively. Endometrial cytology
and culture can be performed at the second oestrous
period after the operation, which allows adequate
time for healing and one oestrous cycle to help natu-
ral resolution of the pre-operative contamination.
The mare can be re-bred by AI 4 weeks post sur-
gery or 3 months post surgery for natural covering.
Complications of the surgical procedure include
total or partial wound breakdown, infection, urine
pooling and constipation.

Prognosis
The prognosis for return to breeding soundness is:
good for first-degree tears; fair for second-degree
lacerations with surgical repair, but guarded if this is
not undertaken; poor for third-degree lacerations if
not treated surgically; and guarded to fair with sur-
gical repair as long as very careful attention to detail
is paid. First- and second-degree tears can occur
at subsequent foalings, but it is unusual for third-
degree tears to do so if they are repaired correctly. Fig. 2.85 This is an unusual form of rectovestibular
fistula seen just prior to surgical repair. The fistula
RECTOVAGINAL/VESTIBULAR FISTULAE has exited through the left edge of the anal ring as
well as the caudal rectum, leaving the perineal body
Definition/overview intact on the right-hand side. (Photo courtesy Graham
Less common than perineal lacerations (p. 476), Munroe)
but similar aetiology with a higher incidence in pri-
miparous mares. Presents as a communicating hole but faecal contamination of the vagina, which is
between the rectal and vaginal cavities, with an quite common, should be removed daily if possible.
intact anus, perineal body and skin. A rectovaginal Some small fistulae can seal spontaneously with
fistula occurs in the vagina cranial to the vestibular wound granulation and contraction. Delays of a
fold, whereas a rectovestibular fistula is caudal to the minimum of 4–6 weeks to allow reduction in inflam-
fold (Fig. 2.85). The latter tends to damage more of mation, second intention healing, granulation,
the perineal body leaving, on some occasions, only wound contracture and tissue fibrosis to occur prior
the perineal skin intact. The size of the fistula can to surgical treatment are based on a similar premise
vary from millimetres (where there has been poor to that for third-degree lacerations. The pre- and
healing of a third-degree perineal tear and subse- postoperative preparation and care are similar and
quent fistulation) to, on average, 5–10 cm. Some of just as important.
the largest are the diameter of a foal’s head. Several different methods of surgical repair have
been described. The intact anal sphincter and peri-
Management neal body can be excised, essentially converting the
The management and treatment of rectovaginal/ fistula into a third-degree laceration, and this is
vestibular fistulae are similar to third-degree peri- repaired by one of the methods described for this
neal lacerations, with a suitable delay to allow trau- injury. This technique is particularly useful where
matic inflammation and tissue damage to subside the perineal body is substantially damaged and
and resolve. Cleaning of the fistula is not possible, it has the advantage of a good exposure and the