Rectal Prolapse - Cat and Dog

Signalment

• No breed predisposition but may occur more often in Manx cats due to anal laxity
• No sex predilection

Description

Rectal prolapse is defined as the protrusion of the rectal mucosa from the anus. It can be classified as complete or incomplete. A complete prolapse involves all layers of the rectal wall whereas an incomplete prolapse only involves the mucosal layer.

Any conditions which cause tenesmus can cause rectal prolapse, this includes:

• Gastrointestinal disease
  • Parasites
  • Tumours
  • Foreign bodies
  • Colitis
  • Megacolon
• Urogenital disease
  • Cystitis
  • Prostatic disease
  • Extensive transitional cell carcinoma of the bladder in cats
• Perineal hernia
• Dystocia

Endoparasite and enteritis are more common in young animals whereas tumours or perineal hernias are more common in middle-aged to older animals.

Diagnosis

Clinical Signs

Protrusion of a red, elongated, swollen cylindrical mass from the anus is seen. It is vital to differentiate a rectal prolapse from an ileocolic intussusception. This can be done by passing a probe adjacent to the anus. With a rectal prolapse, the probe cannot be successfully passed.

The everted tissue becomes oedematous, which prevents it from being retracted back into the pelvic canal. The exposed tissue is vulnerable, and depending on the duration of the prolapse, this can lead to inflammation, haemorrhage, congestion and ulceration.

Laboratory Tests

There are no specific tests required. A faecal analysis can be done to check for an underlying parasitic disease as the cause.

Diagnostic Imaging

This may be used to identify the cause of the prolapse.

Treatment

Medical

This may be suitable for acute prolapse with good tissue viability where it is amenable to manual reduction under general or epidural anaesthesia. A loose purse-string suture should be placed around the anus after reduction for a period of 3-5 days. Prior to manual reduction, the protruded mass should be treated with warm saline lavages, massages and lubrication or hypertonic saline sugar solution to relieve oedema. Tenesmus can be reduced by laxative such as lactulose, faecal softener, and a moist diet. Complications such as tenesmus, dyschezia, haematochezia and recurrence can occur.

Surgery

Rectal resection and anastomosis may be needed in cases where manual reduction is not possible or if the tissue is severely traumatised, devitalised or necrotic. Colopexy can be considered in recurrence cases where multiple attempts of manual reduction have failed. Complications such as anal stricture, faecal incontinence, dehiscence, haemorrhage and infection can occur following surgery.

Prognosis

Prognosis is poor in untreated cases of chronic rectal prolapse. The prognosis for surgical patients is good provided the underlying cause is appropriately addressed.

References

• Fossum, T. W. et. al. (2007) Small Animal Surgery (Third Edition) Mosby Elsevier
• Merck & Co (2008) The Merck Veterinary Manual
• Slatter, D. (2003) Textbook of Small Animal Surgery (Volume 1, Third Edition) Saunders