Avian cellulitis is a bacterial skin infection of birds that is characterized by the presence of subcutaneous fibrinonecrotic plaques and inflammation of the outer skin layers. Cellulitis is primarily caused by avian pathogenic Escherichia coli
(APEC), which is a particular strain of E. coli
that causes systemic disease in poultry in the form of avian colibacillosis. The infection can occur in almost any area of the body of the chicken, but most often involves areas with loose subcutaneous connective tissue, such as on the abdomen, breast, and thighs.
Cellulitis usually occurs in association with a previous disruption of the integrity of the skin, such as an abrasion or open wound, providing a path for bacteria to enter the body and colonize the subcutaneous tissue. Avian cellulitis has been shown to be associated with previous outbreaks of colibacillosis