[en] A total of 282 horses 3 days to 25 months old on 99 farms in the Hidaka district, Hokkaido, were investigated. The clinical manifestations of epiphysitis in the metaphysis and epiphysis included the enlargement of the epiphyseal-metaphyseal region, and heat and pain in the region of swelling. Affected were the distal epiphysis of the third metacarpal and metatarsal bones and the proximal epiphysis of the first phalanx in horses 3 to 5 months old, the distal epiphysis of the tibia in horses 6 to 8 months old, and the distal epiphysis of the radius in horses 8 to 12 months old. Radiographic changes were associated with flaring and lipping of the metaphysis and epiphysis adjacent to the epiphyseal plate, and sclerosis in the epiphysis or metaphysis. They included thickening and crushing of the epiphyseal plate, radiolucency or radiodensity, disorderly trabeculae, and linear radiolucency which agreed with the direction of trabeculae in the metaphysis and epiphysis. Affected horses seemed to be normal at first sight for 7 or 8 months after the onset of disease, but they had several sequelae. Epiphysitis was closely related with the linear radiolucency of the proximal sesamoid bone, radiolucent cyst-like lesions, ataxia, enlargement of the hock, and contraction of tendons. The rate of occurrence of epiphysitis was 27% on 10 farms in the Hidaka district

[en] Most of the bone fractures in racehorses occur in the fore limb, especially in the metacarpal joint during the racing and training. The longitudinal fracture of the third metacarpal bone (Mc III) often occurs in the osteosclerotic and/or necrotic lesions in the distal part of the bone. To elucidate the endogenous factors of its fracture, soft radiograms of 4 fractured and 4 non-fractured control cases have been investigated morphometrically by a image analyzer. In addition, to analyze the quality of these bones, 20 elements of mineral contents in the crashed bones have been measured using a fluorescent X-ray analyzer. As the results, the osteosclerotic change was observed in both groups in the plantar side of the distal part of Mc III, however, no significant differences were found in the bone morphometry. No significant differences in the 19 elements of bone mineral were found except Fe. From these findings, the mechanism of the occurrence of the longitudinal fracture in the Mc III remains to be elucidated. In future, further work needs to be done with regard to the mechanical intensity and collagen disposition of the distal part of the Mc III

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[en] An attempt was made to apply xeroradiography to the fetlock joint of racehorses. As a result, it was possible to detect a focal bone lesion of this joint too small or vague to be demonstrated by the conventional radiography examination. This result suggested that xeroradiography might be useful for detecting early changes in a bone lesion or making an early diagnosis for lesions in the horse, as well as for the observation of the internal bone architecture. (author)

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