Equis ISSN 2398-2977

Rectum: tear

Contributor(s): Timothy Mair, David Moll

Introduction

  • Rectal tears involve damage to the rectal wall, and can result in peritonitis or even death.
  • Cause: they can occur after rectal examination, covering/foaling or may occur spontaneously.
  • Signs: blood on a rectal glove, passage of blood-stained feces and possibly the development of straining and shock.
  • Diagnosis: rectal examination, endoscopy
  • Treatment: is aimed at preventing contamination of the peritoneum, antibiotics usually indicated and in some cases surgery is necessary.
  • Prognosis: depends on the depth and extent of damage.

Pathogenesis

Etiology

  • Iatrogenic, following rectal examination, particularly in fractious/poorly controlled horses.
  • Enema administration, especially in foals   Rectal tear 01: perforation - post-mortem    Rectal tear 02: perforation - post-mortem    Rectal tear 03: perforation - post-mortem  .
  • At mating.
  • At foaling.
  • Spontaneous: possibly associated with abnormal rectal contractility.

Predisposing factors

General
  • Fractious animal.
  • Male.
  • Difficult to control during rectal examination - excessive straining.
  • Inadequate sedation.
  • Mares, generally associated with breeding/foaling.

Specific

  • Insufficient use of lubricant during rectal examinations.
  • Rough rectal examination, failure to keep hand still/remove it during peristaltic waves.
  • Inadequate restraining of horse during rectal examination.
  • Inadequate lubrication during rectal examination.
  • Prior weakness of the rectal wall.

Pathophysiology

  • For the purposes of discussion, rectal tears are classified according to the depth of the tear. This grading takes no account of the length of the tear.
  • Grade 1: tears involving the mucosa only or the mucosa and submucosa.
  • Grade 2: tears involving only the muscularis layers (mucosa intact).
  • Grade 3: tears involving the mucosa, submucosa and muscularis layers:
    • Grade 3a: only serosa left intact.
    • Grade 3b: tears that occur dorsally into the mesorectum   Rectal tear 04: Grade 3b - post-mortem  .
  • Grade 4: tears involving all layers so that there is direct communication with the peritoneum or retroperioneum.
  • Grades 1 and 2 tears can be relatively easy to treat. Grades 3 and 4 tears are more serious and can result in peritonitis   Abdomen: peritonitis  or retroperitoneal abscessation.
  • Although spontaneous and traumatic rectal tears can occur, the majority follow rectal examination that is resented.
  • The majority of rectal examinations are carried out on mares for gynecologic reasons, however colic evaluation and the investigation of undescended testicles also require rectal examination.
  • Males more commonly suffer from rectal tears than females, and their tears are generally more severe.
  • Males may actually have more fragile rectums than females, so may be more susceptible for that reason, as well as because they are often harder to restrain and less used to rectal examination.
  • Fractious horses that strain excessively while being examined are also most susceptible.
  • Straining and peristalsis that is excessive can result in the spasm of the rectal lining, and tearing. The most common site of rectal tears is 25-30 cm in from the anus, where the rectum tends to tear dorsally as the rectum changes course. It would appear that there is a weak spot here.
  • A tear occurring in the most caudal part of the rectum may remain localized in the retroperitoneal area. Leakage of bacteria can   →   retroperitoneal cellulitis if allowed to enter the peritoneum, result in peritonitis.
  • A tear occurring more cranially in the peritoneal part of the rectum or small colon may result in bacterial contamination of the paritoneal cavity and peritonitis.

Timecourse

  • In the case of grade 4 tears, peritonitis, toxemia and circulatory collapse can result within a few hours; euthanasia is indicated.

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.
  • Eastman T Get al(2000)Treatment of grade 3 rectal tears in horses by direct suturing per rectum.Equine Vet Educ12, 32-34 VetMedResource.
  • Mair T S (1999)Spontaneous rupture of the rectum in a pony.Equine Vet Educ11(1), 21-22 VetMedResource.
  • Schumacher J (1999)Rectal tears of horses.Equine Vet Educ11(1), 23-28 VetMedResource.
  • Watkins J Pet al(1989)Rectal tears in the horse - an analysis of 35 cases.Equine Vet J21(3), 186-188 PubMed.

Other sources of information

  • Blikslager A T (2004)How to Manage a Rectal Tear in a Horse.In:Proc 43rd BEVA Congress. Equine Vet J Ltd, Newmarket. pp 229.
  • Mair T, Divers T & Ducharme N (2002)Manual of Equine Gastroenterology.Saunders. ISBN: 0 7020 2486 4.
  • England G C W (1996)Allen's Fertility and Obstetrics in the Horse.Blackwell Science. ISBN: 0 632 04084 X.
  • Rose R J & Hodgson D R (1993)The Manual of Equine Practice.Saunders. ISBN: 0 7216 3739 6.


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