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Basics ⬇

Outline

BASICS

Definition!!navigator!!

A partial- to full-thickness tear in the wall of the retroperitoneal or peritoneal rectum.

Pathophysiology!!navigator!!

Rectal tears are usually a complication of manual palpation per rectum but can also be due to enema administration in foals, dystocia, and breeding accidents. Most tears are longitudinal and located dorsally and 15–55 cm from the anus. The following 4 grades have been described:

  • Grade 1—tearing of the rectal mucosa and submucosa
  • Grade 2—the muscular layer of the rectum is torn, and the intact mucosa and submucosa prolapse through the defect to create a diverticulum, which may act as a pocket for fecal impaction
  • Grade 3a—disruption of the rectal mucosa, submucosa, and muscularis layers, with intact serosa resulting in a palpable void in the rectal wall that exposes the serosa
  • Grade 3b—disruption of the rectal mucosa, submucosa, and muscularis layers, with intact mesorectum and retroperitoneal tissues. This tear is palpable as a defect in the rectal wall that exposes the fat-filled mesorectum. The presence of intact serosa or mesorectum prevents direct contamination of the abdominal cavity with fecal material; however, movement of bacteria through these tissues frequently induces peritonitis
  • Grade 4—tearing of all layers of the rectum; as a result, direct communication exists between the rectum and the abdominal cavity

Systems Affected!!navigator!!

GI

Local and diffuse peritonitis may develop within 2 h of a rectal tear, especially in grade 3b and 4 tears. Ileus secondary to diffusion of bacteria and toxins may follow. Abdominal discomfort and straining may accompany rectal impactions, in horses with grade 2 rectal tears.

Behavioral

Signs of colic secondary to peritonitis and ileus initially that may progress to depression and endotoxic shock.

Cardiovascular

Vascular collapse secondary to endotoxemic shock

Genetics!!navigator!!

None

Incidence/Prevalence!!navigator!!

N/A

Geographic Distribution!!navigator!!

None

Signalment!!navigator!!

Breed Predilections

Mean Age and Range

Any age but horses unaccustomed to rectal examination are at higher risk.

Predominant Sex

More often in mares.

Signs!!navigator!!

General Comments

Tearing of the rectum during a rectal palpation may not be felt, but should be suspected if a significant amount of blood is evident on the rectal sleeve or in the feces following rectal examination.

Historical Findings

Horses with grade 1 or 2 rectal tears rarely show signs. Grade 2 tears are often not identified until signs of rectal impaction develop; grade 3 or 4 rectal tears are often associated with signs of colic, a splinted abdomen, or tachycardia within 2 h following rectal tear.

Physical Examination Findings

See Pathophysiology.

Causes!!navigator!!

  • Rectal palpation
  • Misdirected intromission of a stallion's penis during breeding
  • Enema
  • Meconium extraction
  • Dystocia
  • External trauma
  • Fractures of the pelvis or vertebrae
  • Sodomy
  • Ruptured small colon hematomas
  • Spontaneous

Risk Factors!!navigator!!

Repeated rectal examination.

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

Mucosal irritation may result in a few flecks of blood on the palpation sleeve. Colitis or conditions that compromise the vascular supply of the small colon may produce bloody or malodorous brown fluid on rectal examination.

CBC/Biochemistry/Urinalysis!!navigator!!

Leukocytosis and neutrophilia with a left shift, as well as increases in packed cell volume, blood fibrinogen, TP, sodium, and potassium occur early in the course of grade 3 and 4 rectal tears, as well as leukopenia and neutropenia; decreases in blood potassium, sodium, and chloride levels; and increases in blood urea nitrogen, creatinine, and bilirubin may occur later.

Other Laboratory Tests!!navigator!!

Increased peritoneal fluid, white blood cell count, or TP level are consistent with peritonitis. The presence of degenerate neutrophils, bacteria, or plant material on cytologic examination is indicative of septic peritonitis and is associated with a guarded to poor prognosis.

Imaging!!navigator!!

Abdominal ultrasonography may be useful in assessment of quantity and quality of peritoneal fluid.

Other Diagnostic Procedures!!navigator!!

  • After administration of epidural lidocaine, careful evaluation of the rectum is performed using a bare-arm technique or a surgeon's glove. Buscopan (N-butylscopolammonium bromide) can be administered IV if the horse's systemic condition permits and lidocaine in an enema or jelly can be administered into the rectum. The veterinarian's arm should be lubricated copiously with a water-soluble gel and the feces gently removed from the rectum. The rectal tear should be assessed to determine the severity and distance from the anus
  • A vaginal speculum may be used for visualization of the tear, but in-folding of the mucosa around the end of the speculum often hampers adequate assessment
  • Rectal endoscopy can be useful to grade the tear
  • Laparoscopy is indicated in horses with grade 3 or 4 tears to determine contamination of the abdominal cavity

Pathologic Findings!!navigator!!

See Pathophysiology.

Treatment ⬆ ⬇

Outline

TREATMENT

Aims!!navigator!!

  • Reduce straining
  • Reduce motility
  • Decrease fecal contamination
  • Prevent infection
  • Prevent shock

Appropriate Health Care!!navigator!!

  • Straining and rectal peristalsis should be reduced by sedation, epidural anesthesia, and/or parasympatholytic drugs. A lidocaine enema (12–25 mL of 2% lidocaine in 50 mL water) or lidocaine jelly may be used. Fecal softeners and a laxative diet are valuable in all rectal tear cases
  • Grade 1 rectal tears usually respond well to a 3–5 day course of anti-inflammatory and broad-spectrum antibiotic therapy. Periodic cleaning may be needed to hasten healing and prevent abscess formation, a permanent diverticulum, or a rectal stricture
  • Grade 2 rectal tears may be treated with a gentle lavage of the diverticulum
  • Horses with grade 3a, 3b, or 4 rectal tears should be considered emergencies and referred to a surgical facility
  • Prior to transport, the rectal tear should be packed with 7.5 cm (3 inch) wide stockinette filled with moistened roll cotton. This should be sprayed with povidone–iodine and lubricated with surgical gel and inserted to a point 10 cm proximal to the tear. The anus can be closed with towel clamps or a purse-string suture. Epidural anesthesia to prevent straining and parenteral anti-inflammatory and broad-spectrum antibiotic therapy should be initiated. IV fluids should be given to horses in shock. Feed should be withheld

Nursing Care!!navigator!!

See Appropriate Health Care.

Activity!!navigator!!

Horses treated surgically should be confined to a stall for appropriate postoperative monitoring and management.

Diet!!navigator!!

All horses with rectal tears should be fed a low-bulk laxative diet.

Client Education!!navigator!!

The owner should be informed of the presence of a rectal tear or a suspected tear immediately without acknowledging guilt or responsibility for payment. If treatment is pursued, the owner should be advised of the costs, care, and complications associated with surgical treatment.

Surgical Considerations!!navigator!!

A grade 3 or 4 rectal tear may require surgical placement of a rectal liner, which may be sutured directly or under laparoscopic guidance, or may require a loop colostomy.

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

  • Sedation may be achieved with xylazine 0.2–1.1 mg/kg IV or detomidine 0.005–0.02 mg/kg IV, which can be combined with butorphanol tartrate 0.1 mg/kg IV to enhance duration and sedation
  • Epidural administration of a variety of agents (e.g. lidocaine, xylazine, detomidine) may provide anesthesia for initial evaluation and treatment as well as analgesia for prevention of postoperative straining. A caudal epidural catheter allows repeated drug administration
  • Broad-spectrum antibiotic therapy is recommended for 3–10 days with grade 1 and 2 rectal tears. Extensive broad-spectrum antibiotic therapy is required for grade 3 and 4 tears
  • Tetanus prophylaxis should be considered
  • Flunixin meglumine therapy is recommended for inflammation and endotoxemia

Contraindications!!navigator!!

  • Acepromazine is contraindicated for sedation of hypovolemic horses
  • Indiscriminate use of atropine can result in GI complications, such as prolonged ileus with tympanic distention of the bowel, colic, and tachycardia

Precautions!!navigator!!

Administration of epidural lidocaine may be associated with ataxia.

Possible Interactions!!navigator!!

If sedatives have been administered by the IM or IV route, the epidural dosage of xylazine or detomidine should be adjusted to avoid excessive cumulative sedation.

Alternative Drugs!!navigator!!

N/A

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

  • Horses with grade 1 rectal tears should be monitored closely for 4–8 days
  • Rectal palpation should be avoided for 30 days. Most grade 1 and 2 tears heal within 7–14 days
  • Horses with grade 3 and 4 rectal tears should be monitored for complications associated with the surgical procedure(s) performed. These horses should be assessed with serial CBCs, fibrinogen levels, and peritoneal fluid analyses

Prevention/Avoidance!!navigator!!

  • Rectal examination of horses should be reserved for veterinarians. Rectal examinations should be done only when necessary
  • Appropriate restraint and careful technique should be used
  • Appropriate supervision during breeding may reduce the likelihood of inadvertent tearing by the stallion

Possible Complications!!navigator!!

  • Progression of the tear
  • Fecal contamination of the tear or of the abdomen
  • Peritonitis
  • Extensive cellulitis
  • Abscess formation
  • Rectoperitoneal fistula formation
  • Rectal impaction or stricture
  • Ileus
  • Abdominal adhesions
  • Complications associated with primary closure—excessive tissue trauma
  • Complications associated with temporary liner placement
  • Complications associated with colostomy—dehiscence; adhesions; abscessation; herniation/prolapse

Expected Course and Prognosis!!navigator!!

  • Chances for survival improve with adequate and immediate first aid
  • Grade 1 and 2 rectal tears have a good prognosis
  • Grade 3a tears have a fair to guarded prognosis
  • Grade 3b tears have a guarded to poor prognosis because of the likelihood of greater tissue damage and undermining
  • Grade 4 tears have a poor to grave prognosis because gross fecal contamination of the abdomen predisposes to massive adhesion formation and fatal peritonitis

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

  • Peritonitis
  • Endotoxemia
  • Laminitis
  • Abdominal adhesions

Age-Related Factors!!navigator!!

N/A

Zoonotic Potential!!navigator!!

N/A

Pregnancy/Fertility/Breeding!!navigator!!

Broodmares left with permanent colostomies are prone to intestinal herniation in advanced pregnancy and at parturition owing to unusual abdominal pressures placed against the colonic stoma.

Synonyms!!navigator!!

None

Abbreviations!!navigator!!

  • GI = gastrointestinal
  • TP = total protein

Suggested Reading ⬆ ⬇

Claes A, Ball BA, Brown JA, Kass PH. Evaluation of risk factors, management and outcome associated with rectal tears in horses: 99 cases (1985–2006). J Am Vet Med Assoc 2008;233:1605–1609.

Freeman DE. Rectum and anus. In: Auer JA, Stick JA, eds. Equine Surgery, 4e. St. Louis, MO: WB Saunders, 2012:494–505.

McMaster M, Caldwell F, Schumacher J, et al. A review of equine rectal tears and current methods of treatment. Equine Vet Educ 2015;27:200–208.

Author(s) ⬆

Author: Luis M. Rubio-Martinez

Consulting Editors: Henry Stämpfli and Olimpo Oliver-Espinosa