In chickens and turkeys, a bursa lined with synovial membrane normally exists over the anterior projection of the keel bone. When this bursa becomes inflamed by trauma or infection, fluid or exudate accumulates and appears as a fluid-filled blister 1–3 cm in diameter. Causes of trauma to this bursa include poor feathering, hard flooring, and leg weakness, which is associated with increased recumbency. Some young turkeys have pointed keels, which can lead to increased bursal trauma, but as the size of their breast muscle increases and trauma decreases, lesions may regress. Infectious causes of sternal bursitis include Mycoplasma synoviae, Staphylococcus, and Pasteurella spp.
Last full review/revision March 2012 by Frederic J. Hoerr