Fundamental study on mineral metabolism in race horses with bone fracture

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1. Electron microscopic observation was performed on parathyroid and thyroid glands of 12 race-horses aged 3 to 9 years old which showed motor disturbances. The principal cells of the parathyroid gland were considered to be in the resting phase. On the other hand, the parafollicular cells of the thyroid gland were considered to be in the active phase. From 17 to 11,585 parafollicular cells were counted per 100 mm^2 of thyroid glandsections by immunoperoxidase method.2. Histopathological and biomechanical examinations were performed on bones from limbs of 40 horses suffering bone fracture in racing, and of 69 horses killed for other reasons. The dynamic stiffness and phase-lag (tan ) were measured by a viscoelastic spectrometer. It was suggested that the fractured sample was more brittle than the non-fractured sample.3. Paratholmone (PTH) and calcitonin (CT) levels in the serum were measured on 36 normal, 29 non-fractured and 17 fractured horses by radioimmnoassay. Unusual value were recorded in horses with fracture of large bone.4. Two g of calcium gluconate, 5g calcium chloride and 5g calcium bromide / day was administrated intravenously a horse. Although serum CT level rose highly following the injection, it dropped gradually during a following week. Normal level of PTH and CT were recorded in a horse which was administered same amount of calcium weekly for 16 times. This phenomenor might be due to homeostasis of the living body.5. Pathologic examination was performed on a case of systemic metastatic calcification in a race hose with bone fracture. Low phosphorus and normal calcium and magnesium levels in the serum and bone tissues were recorded. The systemic metastatic calcification might be resulted from nephrosis due to an excessive administration of vitamin D.6. From the results of the present examinations, some part of the mineral metabolism in horse with bone fracture were clarified.