Breast Blister in Chickens: Symptoms, Causes and Prevention

Breast blister is caused by sustained mechanical pressure on the keel bursa from prolonged contact with hard, wet, or abrasive flooring surfaces.

• Wet litter: Moist litter softens and macerates the skin over the keel. Wet litter also harbors bacteria (E. coli, Staphylococcus) that can infect the macerated skin and bursa.
• Hard or abrasive flooring: Wire floors, concrete, or abrasive bedding materials create direct pressure necrosis on the keel bursa. Particularly important in confined birds that spend most of their time recumbent.
• Heavy body weight: Fast-growing broilers generate more keel pressure during recumbent rest than lighter heritage breeds. The heaviest birds in a flock typically have the highest breast blister rates.
• Concurrent leg problems: Birds with perosis, TD, or joint infections spend more time lying down, dramatically increasing keel contact time and breast blister risk.
• High stocking density: Overcrowded birds disturb each other's rest and develop compensatory flooring contact patterns. Competition at feeders forces lower-status birds to spend more time resting on wet, trafficked litter.

Breast blister is diagnosed visually by the characteristic swelling over the keel bone.

• Grading: Palpate and observe the swelling. Grade 1 = fluid-filled, thin-walled, easy to transilluminate. Grade 2 = thicker wall, more viscous fluid, beginning fibrosis. Grade 3 = firm, dark, caseous, no fluid.
• Litter assessment: Check litter moisture at keel level. Wet litter in brooding or resting areas is the most common finding. A simple wet-test: squeeze a handful of litter; if water drips, it is too wet.
• Flock pattern: If multiple birds have breast blisters, it is an environmental management issue, not an individual bird problem. Identify the litter problem before focusing on individual bird treatment.

Litter management is the treatment for breast blister at flock level. Individual bird treatment is appropriate only in pet or breeding birds.

Litter correction: Add fresh dry shavings over wet spots immediately. Consider replacing the top layer of litter in heavily trafficked areas. Identify and fix the water source causing wetness (leaking drinkers, condensation).

Individual bird drainage (Grade 1-2): For pet or valuable birds, aspirate fluid from Grade 1-2 blisters with a sterile needle and apply a light protective bandage. Inject dilute betadine solution and reaspriate if the blister recurs within 48 hours. Repeat 2-3 times if necessary.

Surgical treatment (Grade 3): Fibrous Grade 3 blisters in valuable birds require surgical debridement of caseous material under local anesthesia. Flush the cavity with dilute chlorhexidine and close primarily or leave open to heal by second intention.

Antibiotic coverage: For infected Grade 2-3 blisters (warmth, swelling beyond the bursa, systemic signs), treat with trimethoprim-sulfa or cephalexin orally for 7-10 days.

• Maintain litter depth at 4-6 inches of dry, friable material. Wet litter is both the primary cause of breast blister and the primary risk factor for secondary infection.
• Fix leaking drinkers and nipple lines immediately. A single nipple drip can wet an entire litter pad within hours in a heated brooder environment.
• Reduce stocking density if breast blister rates are elevated. Overcrowded birds have limited access to dry resting areas and distribute weight unevenly across the available floor space.
• Address leg problems promptly. Any condition causing a bird to spend more time lying down (perosis, TD, mycoplasma arthritis) dramatically increases breast blister risk.
• Provide perches for birds over 3-4 weeks old. Perch use reduces time in floor contact and eliminates keel pressure during the rest period.