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Basics ⬇

Basics

Overview

  • Diminution in the size of the rectal or anal lumen either from cicatricial contracture or scarring as a result of wound healing or chronic inflammation or from proliferative neoplastic disease.
  • Gastrointestinal function is compromised because of outflow obstruction.
  • No genetic basis reported.

Signalment

  • Dog and cat
  • No age, breed, or gender predilection reported

Signs

  • Vary with severity of the lesion
  • Tenesmus
  • Dyschezia
  • Constipation
  • Hematochezia
  • Mucoid feces
  • Large-bowel diarrhea
  • Secondary megacolon can develop

Causes & Risk Factors

  • Inflammatory-rectoanal abscess, anal sacculitis, perianal fistulas, proctitis, foreign body, fungal infection (e.g., histoplasmosis, pythiosis).
  • Traumatic-lacerations.
  • Neoplastic-rectal adenocarcinoma, leiomyoma, rectal polyps.
  • Iatrogenic-rectal anastomosis, rectal mass excision, rectal biopsy.
  • Congenital-atresia ani.

Diagnosis ⬆ ⬇

Diagnosis

Differential Diagnosis

  • Space-occupying processes that lead to diminished rectal capacity (extraluminal rectal compression [e.g., prostatic disease, pelvic fractures], intraluminal rectal obstruction [e.g., pseudocoprostasis, foreign body]) and functional constriction (rectal muscle spasms).
  • Differentiate by rectal palpation and imaging.

CBC/Biochemistry/Urinalysis

  • Usually unremarkable.
  • Patients with inflammation or infection may have an inflammatory leukogram.

Other Laboratory Tests

N/A

Imaging

  • Survey abdominal radiography and contrast studies (e.g., barium, air, or double-contrast enema and barium gastrointestinal series) may reveal consistent narrowing of the rectal luminal diameter.
  • A combination of air and barium allows the best visualization of the colonic mucosa and aids in determining the extent of the lesion.
  • Abdominal ultrasonography may reveal thickening and altered architecture if infiltrative rectocolonic disease is present (e.g., pythiosis, neoplasia).

Diagnostic Procedures

  • Digital rectal palpation.
  • Proctoscopy/colonoscopy may be useful to visualize a stricture, determine the extent of the lesion, and procure a biopsy specimen.
  • Colonic scrapings may aid in cytologic diagnosis of fungal (histoplasmosis) and neoplastic diseases.
  • Biopsy and evaluate the lesion histopathologically to classify the disease process and establish a prognosis.

Treatment ⬆ ⬇

Treatment

Medications ⬆ ⬇

Medications

Drug(s)

  • Stool softeners-docusate sodium; lactulose (see Appendix IX for dosages). Intralesional injection of corticosteroids such as triamcinolone prior to dilatation may improve outcome and reduce the likelihood of recurrence. Injection can be repeated one time if additional dilatations are necessary.
  • Corticosteroids-can use prednisone to treat non-infectious inflammatory conditions (0.5–1 mg/kg PO q24h or divided q12h) and after balloon dilation or bougienage to prevent stricture recurrence.
  • Chemotherapy may be indicated for various neoplasms.
  • Antifungal therapy if fungal infection present.
  • Appropriate perioperative antimicrobial therapy with a broad spectrum of activity against anaerobes and coliforms (e.g., cefoxitin sodium 30 mg/kg IV) in conjunction with balloon dilation or surgical therapy.
  • Antibiotics can be administered after dilatation if mucosal tearing occurs (e.g., amoxicillin or metronidazole).

Contraindications/Possible Interactions

  • Corticosteroids when infection is possible.
  • Corticosteroids may adversely affect healing after surgical correction of the stricture.

Follow-Up ⬆ ⬇

Follow-Up

Patient Monitoring

  • Resolution or recurrence of clinical signs.
  • Patients with neoplastic lesions-recurrence and metastatic disease.
  • Patients with strictures that have undergone balloon dilation should be re-evaluated for restricture formation within 7–14 days of the dilation procedure to determine the need for additional dilation procedures.

Possible Complications

  • Medical treatment-can include inefficacy, diarrhea, and adverse effects of medications.
  • Balloon dilation can result in deep rectal tears, hemorrhage, or possibly full-thickness perforation.
  • Surgical treatment-fecal incontinence, secondary stricture formation, and wound dehiscence.

Expected Course and Prognosis

  • Varies with the severity of the stricture.
  • Patients with benign strictures that are readily managed medically or with balloon dilation or bougienage may have a good long-term outcome.
  • Surgical resection has more guarded prognosis because of the frequency of complications.
  • Most patients with recognizable clinical signs due to neoplasia have a guarded-to-poor prognosis for complete resolution.

Miscellaneous ⬆

Miscellaneous

Age-Related Factors

Atresia ani is seen within weeks of birth.

Suggested Reading

Aronson LR. Rectum, anus, perineum. In Tobias KM, Johnston SA, eds, Veterinary Small Animal Surgery, St. Louis, MO: Elsevier Saunders, 2012, pp. 1564–1600.

Culp WT, Macphail CM, Perry JA, Jensen TD. Use of a nitinol stent to palliate a colorectal neoplastic obstruction in a dog. J Am Vet Med Assoc 2011, 239:222–227.