[Tibial dyschondroplasia in meat turkeys: morphometric study of its relationship with lameness]

The tibiotarsal bones from 1,084 15-week-old growing commercial male turkeys, half of which clinically lame, were examined for dyschondroplasia. Lesions were a cone of retained cartilage, confined to the postero-medial area of the proximal metaphysis of the tibiotarsus. Dense woven bone was present around the largest lesions associated with thickening of the diaphyseal cortex below the lesion. Length of abnormal cartilage varied from 0.1 cm to 5.3 cm. Width never exceeded 2.9 cm. Half of the affected turkeys showed unilateral localization of dyschondroplastic lesions. The percentage of damaged tibias was 54 per cent and the percentage of affected turkeys was more than 70 per cent. The incidence of dyschondroplasia was the same in lame and clinically healthy turkeys but, on average, lame turkeys exhibited longer lesions than clinically normal birds. The tibias of lame turkeys were more curved than the tibias of healthy ones as well in the anterio-posterior projection as in the latero-medial one. The latero-medial projection of incurvation was correlated with the length of dyschondroplastic lesions.