Page 501 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

476 CHAPTER 2

VetBooks.ir therapy if dehydration or cardiovascular collapse being pushed through the dorsal vaginal wall and,
in severe cases, into the rectum. If the dorsal vaginal
is evident, oxytocin injections to aid uterine clear-
ance of fluids or retained fetal membranes, and early
implementation of acute laminitis treatment either wall is penetrated, but not the rectum, continued
expulsion leads to damage to the ventral perineal
prophylactically or therapeutically (p. 72). Foal body and dorsal vulva. If the rectum is penetrated,
nutrition should be supported as necessary. but the foot/feet are withdrawn back into the vagina
before further expulsion, then a rectovaginal fistula
Prognosis is created (p. 479). If the rectum is penetrated and
Frequently, the condition initially presents in an the foot/feet are not withdrawn and there is con-
advanced state with a poor prognosis, and early tinued expulsion, then the entire caudal perineal
recognition and aggressive treatment is essential to body, ventral anus and dorsal vulva are destroyed
improve the chances of a recovery. Treatment can (3rd degree perineal laceration). Rarely, the dam-
be prolonged and involve significant expense. The age occurs to the lateral vaginal wall, caudal rectum
condition can be life-threatening with the onset of and anal sphincter.
laminitis a poor prognostic sign.
Clinical presentation
PERINEAL LACERATIONS • First-degree lacerations involve only the mucosa
of the vestibule and dorsal vulval commissure
Definition/overview and are the least severe injury.
Perineal lacerations are common injuries, particu- • Second-degree lacerations affect the mucosa and
larly in the primiparous mare. They are usually submucosa of the vestibule, the dorsal vulval
associated with fetal oversize and malpresentation, skin and some of the perineal muscle.
where one or both forelimbs is/are presented dor- • Third-degree lacerations are the most severe and
sally over the head and neck. Three types of peri- all layers of the dorsal vestibule, perineal body,
neal lacerations occur: first degree, second degree caudal rectum and ventral anus are destroyed.
and third degree (Figs. 2.80–2.84). Careful visual
examination along with rectal and vaginal palpation All of this damage is retroperitoneal, but in rare
will confirm the degree of damage. Treatment var- cases damage can occur more cranially and involve
ies with the degree of damage. Careful attention to the peritoneal cavity, with the possibility of severe
detail in the pre-, intra- and postoperative periods contamination and peritonitis.
is essential to achieve a good surgical success and
return to breeding soundness. Differential diagnosis
Rectovaginal/vestibular fistula; other caudal repro-
Aetiology/pathophysiology ductive tract lacerations.
Perineal lacerations occur at foaling and are more
common in primiparous mares partly due to the Diagnosis
increased likelihood of hymen remnants, espe- Clinical signs and a careful examination visually
cially dorsally, and the increased presence of the and by rectal and vaginal palpation will confirm the
vestibulovaginal sphincter. Fetal oversize and mal- extent of the damage. In cases that are not repaired
presentation are also more common in these mares, immediately, particularly with third-degree lacera-
with a particular problem being where the foal tions, it is important to assess the entire reproductive
is presented in the ‘foot nape’ presentation. The tract, especially the uterus, for damage and endome-
increased prominence of the hymen and/or vestib- tritis. The latter is particularly common due to fae-
ulovaginal sphincter increases the chance of these cal contamination of the caudal tract. Endometrial
forelimbs catching on the dorsal vaginal mucosa cytology, culture and biopsy may be useful in assess-
during parturition and, with continued expulsion, ing this possibility.