Observations on leg deformity in broilers with particular reference to the intertarsal joint.

Leg deformities were investigated in two flocks of male broilers. The most frequently encountered lesions were a progressive valgus deformity of the intertarsal joint, dyschondroplasia and an abnormal thickening of growth plates. No chondrodystrophy was observed. In one flock the peak incidence of leg deformities occurred between 3 and 7 weeks of age and 75% of all valgus abnormalities were diagnosed between 22 and 35 days of age (P < 0.001); 62% of broilers with leg abnormality in this flock had growth plate lesions in one or more bones compared to 40% in broilers without deformity (P < 0.001). Although a relationship is indicated between the presence of dyschondroplasia - particularly in the distal tibio-tarsus - and valgus deformity it was considered that dyschondroplasia would increase the likelihood of distortion without necessarily being a pre-requisite for the initial deformity. The terminology of the lesions is discussed.