Veterinary advice should be sought from your local veterinarian before applying any treatment or vaccine. Not sure who to use? Look up veterinarians who specialize in poultry using our directory listing. Find me a Vet

Cloacal Prolapse

Vent Blow Out, Vent Prolapse

Cloacal prolapse or vent blow out is a potentially life-threatening condition in hens. It occurs when the inner tissues of the cloaca (which serves as an opening for the urinary, reproductive, and gastrointestinal tract) protrude outside of the body. The vent is the final component of the cloaca, which is essentially the 'butt hole'. These prolapsed tissues often attract other birds in the flock, who in turn start pecking at them which leads to potential trauma and secondary infection.

Cloacal prolapses are generally associated with egg laying, although rarely they may be associated with masses/tumors of the reproductive tract.

Treatment of cloacal prolapse

The prolapsed tissues will need to be cleaned and kept moist with a water-soluble lubricant to prevent them from drying out. If they are swollen, applying dimethyl sulfoxide (DMSO) or a solution of 50% dextrose topically to the tissue may help reduce it's size back to normal. Stay sutures may be needed in order to keep it inside the body.

Clinical Signs

Intermittent of persistent mass protruding from the vent
Droppings streaked with blood
Straining appearance
Preening excessively
Picking at vent region
Soiled feathers around the vent (pasty butt)
Foul odor


  • History
  • Clinical signs
  • Physical exam
  • Cytology
  • Bacterial culture
  • Gram stain
  • Radiographs - can be misleading if the egg shell is not mineralized.
  • Ultrasound - useful for detection of eggs, as well as follicular activity and ovarian or uterine masses.


Identify the primary cause
Do not attempt to push the protruded tissue back inside their body yourself. Keep the tissue clean and moist until you are able to get the bird to the vet. Keep isolated from other chickens, to prevent them from pecking at it and causing more damage to the tissue.
Warm saline flushes
If the prolapsed tissue is too swollen, dimethyl sulfoxide (DMSO) and topical dextrose and/or steroids may need to be topically applied to the tissue, in order to decrease the swelling.
Temporary stay sutures
VentplastyA surgical procedure which is done to help decrease the diameter of the vent.
Papilloma removal
CloacopexyMay be needed if the ventplasty has failed to correct the issue, or if the vent diameter and sphincter tone are normal.
Identify the underlying cause


Scientific References

Risk Factors

  • Chronic straining from egg laying
  • Abdominal mass
  • Peritonitis
  • Poor nutrition
  • Obesity
  • Cloacal papilloma
  • Holding droppings for extended periods of time (such as when broody hens are laying on eggs)
  • Cloacitis
  • Diarrhea
  • Constipation
  • Abnormal egg
  • Chronic egg laying
  • Abnormal behavior