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Breast Blister

Keel Lesions, Keel Cysts, Sternal Bursitis

Breast blister (BB), also referred to as keel cyst, is the inflammation of the sternal bursa along the keel bone of the chicken, in the breast area. Chickens suffering from this painful condition develop clear, sticky fluid as fluid-filled blisters that appear as a swelling over the keel bone, sometimes with bruising and discoloration.
There are many factors involved with their development, however they are most often seen in commercial broiler chickens and large meat breed chickens that spend an increased amount of their day laying on their breast area, due to their excessive size. Breast blisters are caused by prolonged contact between the keel and solid surfaces which could be caused by repeated or continuous low-grade trauma, collision-associated trauma, or self-mutilation. Early signs of the development of breast blisters are noticeable thinning of feathers in the area of the keel bone and reddening of the skin. In chronic cases, scar tissue often develops.

Clinical Signs

Blisters, lesions and scabs on breast area
Inflammation (swelling, redness)
Feather loss


  • History
  • Clinical signs
  • Physical exam
  • Culture


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Wound careClean the affected area and flush with antiseptic (1% iodine).
Apply wound dressing.
Supportive careRemove the bird from the pen with the other birds and relocate it inside to a small rehabilitation area with supplemental heat provided.
AntibioticsMay be indicated to prevent secondary bacterial infections.



  • Wrap something soft on roosts
  • Apply padding to walls, fences, or other surfaces which birds have access to in order to reduce injury that may be caused from repeated collision into such structures

Scientific References

Risk Factors

  • Biotin deficiency
  • Weak birds that spend alot of time lying on their sternum or breast bone
  • Birds kept on hard or wire floor
  • Use of coarse or wet bedding
  • Birds with poor feather cover