LOCAL REACTION AND SEROLOGICAL RESPONSE IN COMMERCIAL LAYER CHICKENS INJECTED INTRAMUSCULARLY IN THE LEG WITH OIL-ADJUVANTED MYCOPLASMA-GALLISEPTICUM BACTERIN

The incidence of local vaccine reaction was investigated in three floc ks of commercial layer chickens after they were vaccinated intramuscul arly in the leg with oil-adjuvanted Mycoplasma gallisepticum (MG) bact erin by commercial crews. Local vaccine reaction typically involved sw elling due to a granulomatous cellulitis in the connective tissue abov e the tibiotarsal joint of the vaccinated leg. Histopathology revealed that the inflammatory reaction was confined primarily to subcutis and muscle fascia and rarely extended into muscle fibers, tendons, or ten don sheaths. Movement of the vaccinated flocks from growing to laying houses was associated with a significant increase in the incidence and severity of leg swelling. Antibodies against MG as measured by the he magglutination-inhibition test were significantly higher in chickens w ith severe leg swelling than in chickens without leg swelling.