Growth cartilages with dyschondroplastic foci (osteochondrosis) or areas of chondrolysis were selected from the ribs and bones of the appendicular skeleton of 132 commercial pigs euthanased between one and 169 days old or at a liveweight of 100 kg. Histochemical staining techniques that identified proteoglycans, collagen and deposits of calcium enhanced the visualisation of the lesions, were valuable for recognising the distribution of lesions, and helped to elucidate the development of the lesions. On the basis of the histochemical and morphological differences, it was considered that the lesions associated with growth plates and the lesions associated with articular-epiphyseal cartilage complexes should be considered as different entities. Lesions were identified in the articular-epiphyseal cartilage complexes of pigs at 15 days old, earlier than has been reported previously. Toluidine blue and safranin O were more useful than alcian blue and, in terms of staining intensity, toluidine blue gave more consistent results than safranin O.