Perineal Laceration - Horse

Introduction

Perineal lacerations are a result of foaling injuries.

There are three levels of perineal laceration:

• First Degree Perineal Laceration = damage to skin and mucous membrane only - vulval lacerations should be repaired immediately
• Second Degree Perineal Laceration = damage to skin, mucous membrane and musculature - the wound should be repaired after the formation of granulation tissue
• Third Degree Perineal Laceration = complete perforation of the vaginal wall and rectum producing a single opening to the rectum and vagina

All cases should receive anti-inflammatories, antibiotics and tetanus antitoxin.

Initial Assessment and Stabilisation

(1) Assessment of heart rate and mucous membrane colour (increasing rate and blanching of the mucous membranes indicate possible internal haemorrhage)

(2) Careful palpation of the anterior vagina and rectum (a possible tear into the abdominal cavity or peri-rectal space)

(3) Assess the depth, size and location of the tear and extent of severe deep-tissue injury

(4) Eliminate injury to other pelvic organs if possible (uterine haemorrhage, middle uterine artery tear, prolapsed bladder, injury to the small or large colon by the foal’s hind legs).

Treatment

Treatment of third degree perineal laceration is always surgical and the aim is to restore normal anatomy. Where foaling and injury has occurred less than 3 hours before examination, immediate repair can be investigated but is rarely indicated. Usually severe bruising and laceration are present and repair should be delayed until granulation of the area occurs in 6–8 weeks or even longer.

Preparation for surgery:

• A laxative diet should be fed.
• The horse should be placed in stocks and sedated and restrained appropriately.
• The tail should be wrapped and tied.
• An epidural should be administered.
• The rectum should be emptied and packed to prevent contamination.
• The area should be clipped and scrubbed.
• Dorsolateral and ventrolateral retention sutures should be placed.

There are two techniques for repair of a third degree perineal laceration:

(1) The Aanes technique is a two-stage repair:

• stage 1 reconstructs the recto-vestibular shelf but leaves the perineal body open. The wound is dissected to 2-3cm past the defect and then the shelf is closed in two layers - a simple continuous pattern is used in the tissue beneath the rectal mucosa to invert it and a six-bite interrupted purse-string suture is used to close the perineal shelf and vaginal mucosa.

• stage 2, the perineal body is closed 3–4 weeks later. The site should be infiltrated with local anaesthetic prior to surgery. Excess tissue is removed and the edges of skin are sutured from the anal sphincter to the most ventral point of the incision. To eliminate dead space additional sutures may be placed deep to the perineal body. It is important that no sutures are placed in the anal sphincter. Sutures should be removed after 7-10 days.

(2) The Goetze technique is a single-stage operation: the principle is to evert the rectal mucosa into the rectum and vaginal mucosa into the vagina with a form of purse string suture

Endometrial swabs should be taken once the wound has healed to check for the presence of endometritis.

Prognosis

The outcome is usually good if normal anatomy is restored, allowing normal function.

Reference

Pycock, JF (1997) Self-Assessment Colour Review Equine Reproduction and Stud Medicine Manson

McGladdery, A (2001) Dystocia and post-partum complications in the mare In Practice 2001 23: 74-8

Shepard, C (2010) Post-parturition examination of the foal and mare In Practice 2010 32: 97-10

RVC staff (2009) Urogenital system RVC Intergrated BVetMed Course, Royal Veterinary College