Glucocorticoid-induced bone disorders: nature and mechanisms of glucocorticoid-induced bone disorders in dogs.

Treatment with 5.0 mg/kg of hydrocortisone twice a week for 12 months led to the significant decreased levels of serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D. A histomorphometric evaluation of iliac cortical and trabecular bones was carried out using tetracycline double labelling method and tetrachrome staining. The excessive hydrocortisone treatment produced poor or no fluorescent labelling in the iliac cortex, indicating the absence of any newly established bone. Our present data demonstrate that excessive glucocorticoid may induce bone disorder in dogs by indirectly causing the decrease of serum 1,25-dihydroxyvitamin D3 levels or by directly inhibiting mineral apposition of bone.