Perineal Injury
Basic Information 
Clinical Presentation
Disease Forms/Subtpes
• First-degree perineal injury: Lesions involve only the mucosa of the vestibule and the skin at the dorsal commissure of the vulva.
• Second-degree perineal injury: Lesions involve the vestibular mucosa and submucosa as well as continuing into the musculature of the perineal body (including the constrictor vulvae muscle). The rectum and anal sphincter remain intact.
• Third-degree perineal injury: Lesions penetrate into the rectum through disruption of the rectovestibular shelf. These lesions also continue through the perineal body and anal sphincter and therefore cause a common rectal and vestibular opening.
• Rectovestibular fistula: Lesions penetrate into the rectum through disruption of the rectovestibular shelf; however, the perineal body and anal sphincter remain intact.
History, Chief Complaint
Physical Exam Findings
• Heart rate may be normal or may be elevated.
• Temperature is most frequently normal.
• The mucous membranes are often pale pink and moist.
• May have no colic signs or may demonstrate mild colic signs secondary to constipation and decreased fecal output.
• Swelling, hemorrhage, and pain on palpation of perineal area.
Etiology and Pathophysiology
• Although perineal injuries can be rarely associated with malicious behavior, self–trauma, or breeding injuries, most are associated with foaling.
• Increased risk if there is a persistent hymen or a prominent vestibulovaginal sphincter in mares that are foaling for the first time.
• Passage of the foal’s foot through the vestibule can be hindered by a prominent dorsal transverse fold of the vestibulovaginal junction. If the mare contracts to expel the fetus, the foal’s foot can be forced into the roof of the vestibule causing injury.
Diagnosis 
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