Overview and Clinical Importance
Cloacal prolapse (also termed vent prolapse) is a serious and potentially life-threatening emergency in avian medicine where internal tissues of the cloaca protrude through the vent opening. The cloaca (Latin for "sewer") is the common terminal chamber for the gastrointestinal, urinary, and reproductive systems in birds. Prolapsed tissues may originate from the cloacal wall itself, the oviduct (uterus), or the intestinal tract. This condition requires immediate veterinary intervention as exposed tissues are at risk of trauma, desiccation, infection, and ischemia.
Cloacal prolapse is particularly prevalent in certain psittacine species, especially cockatoos and African grey parrots, and is strongly associated with both reproductive and behavioral factors. Understanding the anatomy, etiology, differential diagnosis, and treatment options is essential for the NAVLE examination.
| Compartment |
Anatomy |
Clinical Significance |
| Coprodeum |
Largest chamber in psittacines. Receives feces from rectum. Flat, avillous mucosa with extensive vasculature. Separated from urodeum by coprodeal fold. |
The coprodeal fold can completely close off during egg laying or ejaculation to prevent contamination. |
| Urodeum |
Smallest chamber. Receives ureters (dorsal midline), oviduct (left dorsolateral in females), ductus deferens (bilateral papillae in males). Smoother, less vascular mucosa. |
Exhibits retroperistalsis, pushing urates into coprodeum/rectum for water reabsorption. Critical for water conservation. |
| Proctodeum |
Final chamber, slightly larger than urodeum. Contains bursa of Fabricius (dorsal wall). Opens to exterior via vent controlled by striated sphincter muscle. |
Most frequent site of papillomas in psittacines. Bursa is site of B-lymphocyte production in young birds. Vent is horizontally flattened ("lip-shaped"). |
Anatomy of the Avian Cloaca
The cloaca is divided into three distinct chambers separated by mucosal folds. The mnemonic "CUP" (Coprodeum, Urodeum, Proctodeum) helps remember the proximal-to-distal arrangement.
High-YieldRemember "CUP" for cloacal anatomy: Coprodeum (feces), Urodeum (urine/reproductive), Proctodeum (exit). Female birds have only a LEFT-sided reproductive tract - the oviduct opens on the left dorsolateral wall of the urodeum. This is critical for identifying oviductal prolapse!
| Category |
Contributing Factors |
| Reproductive |
Chronic egg laying, dystocia/egg binding, abnormal eggs, oviductal masses/neoplasia, chronic masturbatory behavior |
| Gastrointestinal |
Constipation, diarrhea, cloacitis, cloacal papillomatosis, intussusception, intestinal parasites, GI foreign body |
| Nutritional |
Hypocalcemia (reduces smooth muscle tone), vitamin A deficiency, obesity, poor diet leading to protein/calcium depletion |
| Behavioral |
Inappropriate human-bird bonding (mate behavior), sexual stimulation by owners, delayed weaning, prolonged fecal retention |
| Other |
Space-occupying abdominal masses, peritonitis, cloacoliths, neoplasia, nerve damage affecting sphincter |
Etiology and Risk Factors
The proximate cause for cloacal prolapse is chronic straining and/or loss of normal cloacal sphincter tone. Multiple underlying factors can contribute to this condition.
Primary Etiologies
Species and Breed Predisposition
NAVLE TipRemember: "Cockatoo = Cloacal Chronic" - Cockatoos (especially Umbrella and Moluccan) are MOST predisposed to chronic cloacal prolapse due to behavioral factors. Hand-raised cockatoos with strong human bonds are at highest risk. Cockatoos that live independently of humans typically do NOT develop this condition!
| Species |
Primary Etiology |
Notes |
| Umbrella/Moluccan Cockatoos |
Behavioral/Idiopathic |
MOST commonly affected. Males more than females. Strong association with human bonding. |
| African Grey Parrots |
Behavioral/Chronic |
Second most affected psittacine. May have concurrent hypocalcemia. |
| Cockatiels, Budgies, Lovebirds |
Oviductal prolapse |
Most common for egg-related prolapses. Chronic egg layers predisposed. |
| Poultry (Chickens) |
Oviductal/Cloacal |
Associated with large eggs, chronic laying, hypocalcemia. Risk of cannibalism. |
Clinical Signs and Presentation
Birds with cloacal prolapse may present with varying degrees of illness. The prolapse may be intermittent or persistent. Clinical signs include:
- Visible tissue protrusion from the vent - pink/red when acute, may become dark/black if chronic or necrotic
- Depression, lethargy, fluffed appearance
- Straining/tenesmus
- Decreased or absent droppings
- Hematochezia (blood in droppings)
- Soiled feathers around the vent
- Foul-smelling droppings (if infected)
- Dyspnea (tail-bobbing) - especially with concurrent egg binding
| Tissue Origin |
Appearance |
Key Features |
| Cloacal Prolapse |
Red, SMOOTH, rounded, glistening mucosa ("ball-like"). Short protrusion. |
Cannot pass cotton-tipped applicator between prolapse and vent sphincter - NO space. |
| Oviductal Prolapse |
Tubular with visible LONGITUDINAL FOLDS. "Donut-like" with visible lumen. Can extend 1-10 cm. |
Appears on LEFT side. Cloacal lining normal around prolapsed tissue. |
| Rectal Prolapse |
Tubular structure DEVOID of folds. |
Rare. Serious underlying pathology. Can insert applicator into lumen but NOT around sides. |
| Cloacal Papilloma |
ROUGH, irregular surface. Attached to cloacal wall. |
Apply acetic acid - turns white. History of recurrent "prolapses" over months. |
Differential Diagnosis: Identifying Prolapsed Tissue
Critical for NAVLE: You must be able to differentiate the origin of prolapsed tissue based on its appearance.
High-YieldOviductal prolapse = LONGITUDINAL FOLDS + LEFT-sided + "donut" appearance. Cloacal prolapse = SMOOTH, ROUNDED, "ball-like" with NO space between tissue and vent. Papilloma = ROUGH surface that turns white with acetic acid.
| Hypertonic Agent |
Mechanism/Notes |
| 50% Dextrose |
Apply topically - osmotic effect draws fluid out. Rinse after swelling reduced. |
| Hypertonic Saline |
Alternative osmotic agent. |
| Granulated Sugar |
Home first-aid option when other agents unavailable. |
Emergency Treatment Protocol
Cloacal prolapse is an EMERGENCY. Prolapsed tissues must be reduced as soon as possible to prevent trauma, infection, desiccation, and ischemia/necrosis.
Step-by-Step Emergency Stabilization
1. Initial Assessment
- Assess stability - may require IV/IO fluids, warmth, oxygen
- Apply water-soluble lubricant liberally to keep exposed tissues moist
- Induce general anesthesia (isoflurane)
- Place patient in dorsal recumbency
2. Tissue Preparation
- Gently clean tissues with sterile saline and dilute chlorhexidine
- Swab for bacterial culture
- If edematous: Apply hypertonic solution to reduce swelling
3. Egg Management (if present)
If egg present, perform ovocentesis: Insert 18-gauge needle to aspirate contents, apply lateral pressure to collapse shell.
4. Prolapse Reduction
CRITICAL: Do NOT "stuff" tissues back. Tissues must be inverted into anatomically correct orientation - like turning a sock inside out. Use lubricated, blunt probe or gloved finger.
5. Stay Sutures
Place 2-3 simple interrupted or horizontal mattress sutures across vent using 3-0 to 5-0 non-absorbable monofilament (nylon/PDS). Make small, shallow bites.
High-YieldPURSE-STRING SUTURES ARE NOT RECOMMENDED IN BIRDS due to reports of cloacal atony. Use simple interrupted or horizontal mattress sutures. Leave lubricated cotton-tipped applicator in place while suturing to ensure adequate opening for droppings.
| Drug Category |
Drug/Dose |
Notes |
| Anti-inflammatory |
Meloxicam 0.2-0.5 mg/kg PO/IM/SC q12-24h |
Essential post-reduction for analgesia. |
| Antibiotics |
Based on culture/sensitivity |
Prevent/treat secondary infection. |
| Stool Softener |
Lactulose 200 mg/kg PO q8-12h |
Reduce straining during defecation. |
| Calcium |
Calcium gluconate 50-100 mg/kg IM/SC |
For hypocalcemia. Restores smooth muscle tone. |
| GnRH Agonist |
Leuprolide acetate 100-800 mcg/kg IM q2-4 weeks |
Suppresses reproductive hormones. Duration 2-3 weeks. |
| GnRH Agonist (alt) |
Deslorelin implant 4.7 mg SC |
Longer duration (approximately 3 months). |
Medical Management
| Procedure |
Description |
Indications |
| Cloacoplasty |
Excision of mucocutaneous junction to reduce vent opening by 50-75%. |
Chronic recurrent prolapse. Asymmetrical technique creates midline barrier. |
| Percutaneous Cloacopexy |
Full-thickness sutures through abdominal wall and cloaca. |
Less invasive, temporary support. Place lateral to linea alba. |
| Open Cloacopexy |
Via celiotomy, anchor cloaca to ribs, pubic bone, or sternum. |
More permanent. Complication: colonic entrapment. |
| Salpingohysterectomy |
Surgical removal of oviduct. |
Oviductal prolapse, prevent future dystocia. |
Surgical Treatment Options
Behavioral and Environmental Management
CRITICAL FOR SUCCESS: Without addressing behavioral and environmental factors, especially in cockatoos, prolapse will recur regardless of medical/surgical intervention.
- Decrease photoperiod to 8 hours or less of light per day
- Remove perceived nesting sites - nest boxes, dark spaces, paper for shredding
- Dietary modification - pelleted diet, energy-restricted, improve calcium/protein
- Break inappropriate human-bird bonds:
- Stop petting bird's body (especially back) - head only
- Stop hand-feeding warm foods
- Stop cuddling bird close to body
- Discourage regurgitation behavior
NAVLE TipIf the bird still perceives the owner as a mate or parent, it will continue to strain and prolapse WILL recur. This is why cockatoos living independently of humans do NOT develop this condition. Owners often unwilling to modify behavior - the bird's cuddly nature is why they are attracted to it.
Prognosis
- Good to fair with prompt treatment if underlying cause addressed
- Depends on tissue viability, underlying etiology, owner compliance
- Oviductal prolapse - most guarded (40% success in one study)
- Necrotic tissue - poor prognosis, requires surgical resection
- Recurrence common without behavioral modification
"CUP" = Cloacal Anatomy: Coprodeum (feces), Urodeum (urine/reproductive), Proctodeum (exit via vent)
"SMOOTH vs FOLDED": SMOOTH = Cloacal prolapse; FOLDED (longitudinal) = Oviductal prolapse (LEFT side)
"No PURSE for Birds": No purse-string sutures in birds - use simple interrupted or horizontal mattress