Facial cellulitis induced in chickens by Mycoplasma gallisepticum bacterin and its treatment

Ten-to-14-day-old replacement chickens were vaccinated subcutaneously in the neck with a Mycoplasma gallisepticum bacterin. A few days later, 40% of the flock developed cellulitis of the head. Birds were submitted for diagnostic investigation between 4 and 6 wk of age. Histology revealed lesions in the subcutis consistent with oil-emulsified vaccine/bacterin reaction. No significant bacteria were isolated from the lesions. Birds were treated with 1 mg of methyl prednisol acetate intramuscularly. Improvement was noted as early as 12 hr posttreatment. One week after treatment only 1%-2% of the flock still had facial cellulitis.