Perirectal abscesses are uncommon in horses. However, when they occur they often result in abdominal discomfort due to a fecal impaction of the large colon resulting from extraluminal obstruction of the rectum. Horses with perirectal abscessation typically present with a history of mild, intermittent colic, tenesmus, depression, anorexia, and decreased fecal production. Occasionally, mucopurulent material is found coating the feces, and there may be visible protrusion of the anus. Other differential diagnoses that must be considered for a partial or total rectal obstruction in a horse include primary anorectal lymphadenopathy, rectal stricture, hematoma, and neoplasia. A presumptive diagnosis is often made based on rectal palpation findings and ultrasonographic examination. Diagnosis is confirmed with aspiration cytology and culture. Perirectal abscesses may be resolved with medical management alone, especially in young horses, or may require surgical drainage. The type of treatment required is determined by size, location, chronicity, and involvement of adjacent structures and most often includes broad-spectrum antimicrobials, NSAIDs, and stool-softening strategies. Prognosis is good in uncomplicated cases.
Read more about Other Common Equine Emergencies, Overview of Colic in Horses, and Diseases Associated with Colic by Anatomic Location in The Manuals.
References
Ayers SL, Wagner P. Perirectal abscess in an American Miniature horse. Equine Practice 1994;16(9):33-35.
Magee AA, Ragle CA, Hines MT, et al. Anorectal lymphadenopathy causing colic, perirectal abscesses, or both in five young horses. J Am Vet Med Assoc 1997;210(6):804-807.
Torkelson J. Perirectal abscess, colic, and dyschezia in a horse. Can Vet J. 2002 Feb;43(2):127-128.09.
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