Dyschondroplasias, including osteochondrosis, in boars between 25 and 169 days of age: Radiologic changes

SUMMARY Boars in 6 different groups ((between 25 and 169 days of age) were examined radiographically to determine the age of onset of lesions associated with the sites of endochondral ossification in limb bones. Although lesions were in histopathologic sections of physes from all groups of pigs, they were not found frequently in radiographs of live animals until boars were more than 100 days old. Microscopic lesions were infrequent in articular-epiphyseal (a-e) complexes of pigs < 80 days old, and radiographic examination of live animals had limited value until animals were > 100 days old. Radiographs of slabs of bone were useful in the detection of physes with lesions in all age groups and a-e complexes with lesions in boars 100 days of age or older. So that the accuracy of radiographic examination of live animals for the diagnosis of dyschondroplasias could be evaluated, a comparison was made between the numbers of growth cartilages with lesions as determined by radiologic examination of live animals, radiographic examination of slabs of bone, and light microscopy (examination of tissue sections). Only 21% of the lesions associated with physes and 22% of the lesions associated with a-e complexes were detected in radiographs of bones of live pigs. The authors concluded that the latter method was inaccurate for the identification of dyschondroplastic foci. Identification of lesions by examination of radiographs of slabs of bone was only slightly more accurate, since 33% of physes and 23% of a-e complexes which had lesions were found. Potential errors in evaluation of radiographs were discussed. Despite the limited diagnostic value that radiographs of live boars have for dyschondroplasias, these radiographs used in conjunction with those of slabs of bone enabled the authors to estimate the age of lesions. Lesions in histopathologic sections were associated with the physes of the youngest pigs and by using the depths of lesions in radiographs of slabs of bone to estimate ages of lesions, it was hypothesized that the age of onset was < 14 days. Lesions associated with physes and a-e complexes apparently developed continuously and regressed as the pigs grew.