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Perineum: trauma
Synonym(s): Rectovaginal injuries
Introduction
- Perineal injuries/lacerations are associated with parturition.
- Cause: dystocia (malpresentation or occasionally oversized fetus), extensive vigorous manual manipulation during foaling, violent expulsive efforts by the mare.
- Signs: dystocia; depending on degree of injury/tear one or both forefeet and/or head may be presented via rectum.
- Diagnosis: attempt to detect before perforation occurs.
- Treatment: repel foal and redirect limbs; repair severe lacerations after 4-6 weeks.
- Prognosis: depends on degree of injury; good after appropriate treatment.
Presenting signs
- Foal's foot and/or head fails to pass vaginovestibular sphincter and is propelled dorsally.
- Depends on grade of tear:
- First-degree laceration: mucosa of vestibule and skin of dorsal commissure of vulva damaged
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- First-degree laceration: mucosa of vestibule and skin of dorsal commissure of vulva damaged
- Second-degree laceration: mucosa and submucosa of the dorsal vulva, and some of the musculature of the perineal body are damaged (commonly the constrictor vulvae muscle).
- Third-degree laceration: tearing of the ceiling of vestibule and sometimes of the vaginal wall, damage to the perineal septum and muscles and the floor of the rectum, creating an opening between the rectum and vestibule. Anal sphincter may also be damaged
. - Rectovestibular/vaginal fistula: occurs when the ceiling of the vagina and the floor of the rectum have been damaged/torn (causing a connection between them), but the anal sphincter is intact.
Acute presentation
- Acute presentation during foaling.
Geographic incidence
- Worldwide.
Age predisposition
- Adult - usually maiden foaling mares (primiparous).
Cost considerations
- Usually requires surgical repair - third degree lacerations may be relatively expensive as are some rectovestibular fistulae.
Pathogenesis
Etiology
- Forefoot of foal catches on dorsal transverse fold of vestibulovaginal junction.
- Viable fetus may remove foot voluntarily → unimpeded delivery.
- Continued expulsion with no redirection of foot can drive foot and/or head through dorsum of vestibule and into rectum.
Predisposing factors
General
- Primiparous mare.
- Malpositioned fetus Reproduction: dystocia.
- Oversized fetus.
- Overzealous assistance during foaling Reproduction: foaling management.
Specific
- Prominence of vaginovestibular sphincter and hymen remnants in primiparous mares.
Pathophysiology
- Foot of foal fails to pass vaginovestibular sphincter normally and is propelled caudodorsally.
- This may cause first, second or third degree perineal laceration, or a rectovaginal fistula.
- If presentation of foal not corrected can → third-degree perineal laceration.
- If second or third-degree lacerations not repaired → muscles will not heal and constrictor function of vulva will be lost → air and feces aspirated into vulva and vagina → chronic irritation, inflammation and infertility Uterus: endometritis - bacterial Vulva: Caslick operation.
- In rare cases laceration may extend into the abdominal cavity → peritonitis Abdomen: peritonitis → prolapsed intestines into vagina.
Timecourse
- Acute presentation during parturition.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Schumacher J, Schumacher J & Blanchard T (1992) Comparison of endometrium before and after repair of third-degree rectovestibular lacerations in mares. JAVMA 200 (9), 1336-1338 PubMed.
- Colbern G T, Aanes W A & Stashak T S (1985) Surgical management of perineal lacerations and rectovestibular fistulae in the mare - a retrospective study of 47 cases. JAVMA 186 (3), 265-269 PubMed.
Other sources of information
- Freeman D E (2014) Reproductive Tract Trauma. In: Proc BEVA Congress. UK. pp 72.
- McKinnon A O & Jalim S L (2011) Surgery of the Caudal Reproductive Tract. In: Equine Reproduction. Eds: McKinnon A O, Squires E L, Vaala W E & Varner D V. Blackwell Publishing Ltd. pp 2552-2557.
- Frazer G S (2004) How to Manage Acute Perineal Trauma in a Foaling Mare. In: Proc 43rd BEVA Congress. Equine Vet J Ltd, UK. pp 228.
- Sutter W W, Hooper S & Embertson R M (2003) Diagnosis and Surgical Treatment of Uterine Lacerations in Mares (33 cases). In: Proc AAEP. pp 357-359.
- Held P & Blackford J (1997) Surgical Repair of Abnormalities of the Female Reproductive Organ. In: Current Therapy in Large Animal Theriogenology. Eds: Youngquist R S. pp 195-208.