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.

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

Treatment

Prevention

Outcomes