Avian cloacal prolapses (Proceedings)

Prolapses from the cloaca can be a serious and often life-threatening condition in birds. These may originate from the cloacal wall, reproductive tract, or intestine. Cloacal prolapse may occur secondary to chronic straining from masturbation, egg laying, space-occupying abdominal masses, and inappropriate weaning and social behavior. Prolapsed tissues are at risk of trauma, desiccation, infection, and ischemia. Affected birds should receive immediate medical attention. Prognosis depends on properly identifying the prolapsed tissue and initiating appropriate therapy in a timely manner.

Anatomy

The cloaca (Latin for sewer) is the common opening for the urinary, reproductive, and gastrointestinal tract of birds. It is divided into three chambers: the coprodeum, urodeum, and proctodeum (from proximal to distal, the first letters spell "CUP"). The coprodeum is the chamber into which the rectum empties. It is the largest chamber of the psittacine cloaca. It has flat, avillous mucosa and extensive vasculature. It is separated from the second chamber, the urodeum, by an encircling sphincter-like ridge, the coprodeal fold. This fold can completely close off the coprodeum from the other chambers of the cloaca, preventing contamination of eggs or semen during egg laying or ejaculation.

The urodeum is the smallest cloacal chamber in psittacines. It receives the ureters, the oviduct (females), and ductus deferens (males). The ureters enter the urodeum on either side of the dorsal midline. In females, the oviduct has a rosette-like opening on the left dorsolateral wall. In males the ductus deferens enters the urodeum on symmetrical, raised papillae located on the left and right dorsolateral walls. It is separated distally from the proctodeum by the uroproctodeal fold. The urodeal mucosa is smoother and less vascular than that of the coprodeum. The urodeum exhibits retroperistalsis, pushing urates and urine cranially into the coprodeum and rectum, where water and solutes are further resorbed, thus maximizing water conservation.

The proctodeum is the final cloacal chamber and is slightly larger than the urodeum in most birds. It is the most frequent site of papillomas in psittacines. It gives rise to the bursa of Fabricus on the dorsal midline, just caudal to the uroproctodeal fold. The bursa is the site of B-lymphocyte production in young birds. In mature birds the lymphoid tissue involutes, but the bursal chamber frequently persists and can be viewed during cloacoscopy.

The vent is the final structure of the cloaca. It is the transverse opening in the ventrocaudal body wall, through which body wastes and reproductive products are expelled. It is comprised of dorsal and ventral lips, and surrounded by voluntary muscles that form a sphincter.

Clinical presentation

Because of their stoic nature, affected birds often behave normally. Birds with advanced lesions may present depressed, fluffed, and less vocal. Affected birds may exhibit inappetence, inactivity, or dyspnea signified by tail-bobbing or open-mouth breathing. There may be scant feces or droppings streaked with blood. Birds may appear to strain, groom excessively, or pick at the vent region, and there will be an intermittent or persistent mass protruding from the vent. Feathers around the vent will almost always be soiled with feces or urates. With concurrent Clostridium infection, there may be gas and offensive odor.

Etiology

The proximate cause for cloacal prolapse in most cases is straining and/or loss of normal cloacal sphincter tone. Factors that potentially lead to cloacal prolapse include poor nutrition, obesity, cloacal papilloma, cloacitis, constipation, diarrhea, peritonitis, abdominal mass, abnormal egg, chronic egg laying, and behavioral abnormalities.

Diagnosis

Physical examination should include abdominal palpation for a mass. Cytology and bacterial culture should be performed on prolapsed tissue to aid in antibiotic therapy. A fecal wet mount and Gram stain are also recommended. A complete inspection of the cloaca should be performed, usually under general anesthesia. If possible, a vaginal speculum and strong light source should be used to permit examination deep into the cloacal cavity. CBC, chemistry panel, radiographs, ultrasound, and endoscopic exam are useful to determine predisposing causes.

Identification of tissue

Rectal/intestinal

Rectal prolapses can occur from intusussception, intestinal obstruction, intestinal masses, chronic straining, or severe diarrhea. Rectal prolapse is more common than intestinal prolapse. Rectal prolapse can be identified as a tubular structure devoid of longitudinal folds, centrally located within the cloaca. The cloaca itself should be normal in appearance. It is difficult to differentiate intestinal prolapse from rectal prolapse. For rectal prolapse it should be possible to insert a lubricated cotton-tipped applicator into the lumen, but not on either side of the prolapsed loop. If a cotton-tipped applicator can be inserted into the lumen and also into the folds surrounding the prolapse, then intestinal prolapse should be suspected.

Rectal and intestinal prolapses are rare and in most cases result from serious and life-threatening problems. Fecal Gram stain, radiographs, and contrast studies may be helpful to establish a potential etiology. Treatment should be directed at the specific etiology. In most cases reduction of the prolapse will need to be accompanied by surgery to remove a foreign body, biopsy or remove a mass, or reduce an intusussception.

Reproductive

Female birds have a reproductive tract on the left side only. The oviduct is a tubular structure with longitudinal folds that are usually visible on the lumen. Prolapses are generally associated with egg laying, although rarely they may be associated with masses/tumors of the reproductive tract. When prolapsed, the tissue may become edematous, but a lumen should be clearly identifiable, and in most cases it will be possible to see the longitudinal folds. The tissue should appear on the left side of the bird, and the cloacal lining itself should also be evident and normal, with the prolapsed tissue protruding through the cloacal cavity.

Treatment of reproductive tract prolapse is always directed at identification and resolution of the primary disease process. In most cases, this will be associated with egg laying. It is essential to thoroughly evaluate for the presence of a retained egg or egg fragments. Radiographs should always be performed, but can be misleading if the egg shell is not mineralized. Ultrasound is very useful for detection of eggs, as well as follicular activity and ovarian or uterine masses. In cases where there appears to be caudodorsal enlargement or a mass effect, or the location of enlargement cannot be determined, then contrast radiographs can be useful in differentiating the intestines and the region of enlargement/mass. If there is an obvious egg within the prolapsed mass, then it can be collapsed or surgically removed. Salpingohysterectomy is recommended to prevent future episodes of egg retention and prolapse.

Cloacal

A prolapsed cloaca most commonly occurs due to either papillomatous disease or sexual behaviors (typically males). It often begins as a mild prolapse which the bird seems to be able to control voluntarily, and eventually leads to persistent prolapse. Examination of the cloaca may reveal one or several fleshy masses at the mucosal border, papillomas having a cobblestone or "raspberry-like" appearance. Some papillomas are pedunculated and intermittently extrude from and retract back into the cloaca. Papillomas can cause mechanical obstruction of the cloaca, resulting in infertility, hematochezia, straining, fecal retention, and secondary bacterial (clostridial) cloacitis.

A quick in-house test can be performed by applying white vinegar to the suspected tissue; if it is a papilloma it will blanch. A complete exam should be performed to rule out oropharyngeal and laryngeal papillomas. Medical evaluation should include fecal Gram stain (check for spore-forming rods), CBC/chemistry profile, and radiographs to check for the presence of a mass or any other abnormality. A thorough endoscopic exam of the cloaca should be performed to rule out obstruction of the gastrointestinal, urinary and reproductive tracts. Diagnosis should be confirmed by biopsy.

Behavioral prolapse of the cloaca is most common in cockatoos and other Old World psittacines; males are more often affected than females. It is often associated with reduced sphincter tone, and affected birds typically show obvious sexual behavior towards and individual or individuals. These prolapses may be chronic, and cloacitis is a common secondary finding. Although prolapsed cloacal tissue may be inflamed, it will appear red, smooth, and rounded like a ball; rectal or urogenital orifices may be identifiable on the prolapse surface. A cotton-tipped applicator cannot be placed between a prolapsed cloaca and the vent sphincter; there is no space in this region with prolapse of the cloaca.

A detailed evaluation of the home environment and human-bird interactions is essential. Any behaviors or situations that the bird may perceive as sexual stimuli must be completely eliminated. This includes stroking of the back and dorsal tail feathers (mimics mating), cuddling and covering the bird (mimics nesting), and feeding of any warm soft food items (mimics regurgitation by mate). Any perceived "nest sites" in the environment also need to be removed; the bird should not be permitted to shred paper, to have a hide box, or seek out cabinets, corners, and similar spaces. Birds with a behavioral prolapse should not have access to perceived mates (stuffed toys, feather toys), including individuals it reacts to sexually. The GNRH agonist leuprolide acetate (Lupron) can also be administered to lower sex hormone activity.

Treatment

First aid

Regardless of origin, prolapsed tissues should be lavaged and lubricated with a water-soluble lubricant to prevent desiccation. If edematous, solutions such as 50% dextrose or DMSO can be applied topically to try to alleviate some of the edema. Tissues should be replaced as soon as possible to prevent infection and necrosis. However, in many cases, this may not be possible until the underlying problem is corrected. Even when the prolapse can be reduced, the underlying problem must still be identified and addressed. Prolapses must be reduced into anatomically correct orientation; it is essential to identify the opening of the intestines and maintain patency. Tissue should invert back into normal position inside the cloacal cavity, as if putting a pants pocket back into place. Stay sutures may be placed in order to prevent immediate reprolapse.

Surgery

Temporary stay sutures

Are indicated to prevent reprolapse of tissue, and to allow enough time for treatment to reduce inflammation, swelling, and infection. Pursestring sutures are not recommended for birds. Instead, two simple interrupted sutures are placed equidistant across the cloaca at approximately one-thirds and two-thirds the distance across the cloacal opening, allowing sufficient space for droppings to pass through. Test patency with a lubricated cotton-tipped applicator or feeding tube, and monitor for normal defecation post-operatively.

Papilloma removal

Can be accomplished using radiosurgery, laser surgery, cryosurgery, or chemical cautery. Due to the vascularity and tendency of cloacal papillomas to bleed, scissor and scalpel surgery are not advised. When cauterizing papillomatous tissue with silver nitrate, it is important to flush the area profusely with saline once sufficient tissue has been cauterized, otherwise normal cloacal tissue will be damaged. Topical medications such as DMSO and silver sulfadiazine should be applied to affected tissue after cauterization. Analgesics should be administered postoperatively as well as antibiotics if there is an associated cloacitis. Recurrence is extremely common and frequent re-examinations are necessary.

Ventplasty

If cloacal prolapse is associated with atony of the vent sphincter, decreasing the diameter of the vent by performing a ventplasty may be indicated. This may be accomplished by one of two procedures. The first procedure involves excision of one or two wedges of skin and subcutaneous tissue from the superficial surface of the vent without traumatizing the muscular or nervous tissue. Close muscle and skin in a 2- or 3-layer closure with fine, absorbable monofilament suture. The other procedure involves incising one-half to three-fourths of the margin of the circumference of the vent to provide a cut surface for healing. The cut surfaces are apposed with simple interrupted sutures to partially close the vent opening, thereby preventing prolapse of the cloaca. A cotton-tipped applicator or feeding tube should easily pass through the resultant opening. Monitor for defecation postoperatively. Incontinence or stenosis are possible sequellae, and may be permanent.

Cloacopexy

If vent diameter and sphincter tone are normal, or a ventplasty has failed to resolve the chronic prolapse, then cloacopexy may be indicated. Since many cases of cloacal prolapse are attributed to nutritional and/or behavioral causes, cloacopexy only addresses clinical signs. Underlying causes need to be addressed. Without concurrent behavioral modification and hormonal manipulation, cloacopexy often fails, with reprolapse occurring weeks to months after surgery.

Percutaneous cloacopexy offers a temporary, less-invasive solution than the more invasive procedures later described, but often supplies sufficient support to allow for the institution of medical and environmental therapy. The patient is placed in dorsal recumbency and the abdomen is surgically prepared. A lubricated, gloved index finger is inserted into the cloaca and pressed against the ventral abdominal surface in order to displace intracoelomic organs and prevent entrapment between the abdominal and cloacal walls. Two to three percutaneous, full-thickness cloacal sutures are placed using monofilament nylon. Suture placement is restricted to the ventral aspect of the body wall, directly lateral to the linea alba, in order to avoid entrapment or perforation of the ureters, rectum, duodenum, or pancreas. If fecal material is not produced within a reasonable period postoperatively, then removal of the most cranial cloacopexy suture should be considered: the distal colon may have folded on itself resulting in a functional colonic obstruction.

For severe cloacal prolapses, cloacopexy is performed using a celiotomy approach. Using a ventral midline or transverse abdominal incision (or a combination of both!), the cloaca is variously anchored to the last rib(s), the pubic bone(s), the caudal edge of the sternum, the abdominal wall, and/or the abdominal incision. The goal is to generate enough tension that slight inversion of the vent opening occurs. For proper adhesion to develop cloacal fat needs to be thoroughly removed and, ideally, the serosa of the apposing surfaces should be peeled back and sutured together. Additionally, stay sutures must penetrate the cloaca (full-thickness) and be pulled tight enough that no space remains to permit bowel entrapment. With successful cloacopexy, adhesions form at the suture sites, keeping the cloaca within the abdominal cavity, however abnormal defecation/micturition and chronic soiling of the vent area may result.

References

Harrison GL, Lightfoot TL. Clinical Avian Medicine, Palm Beach: Spix Publishing, 2006

Antinoff N. Sagging down under: cloacal prolapse, Proc of the North Am Vet Conf. 2000: 1677-1678.

Ritchie BW, Harrison GJ, Harrison LR. Avian Medicine: Principles and Application. Lake Worth, Florida: Wingers Publishing, 1994.

Altman R, Clubb S, Dorrestein G, and Quesenberry K, Eds. Avian Medicine and Surgery. Philadelphia: WB Saunders, 1997.