Radiological and pathochemical characteristics of osteoporosis process in rabbits

Abstract

Various bone and joint pathology is quite common among companion animals, a significant risk factor for which is considered to be a violation of bone metabolism. The aim of the work is to determine radiological and pathochemical criteria in the dynamics of osteoporosis process in the model of rabbits. The experimental (n = 18) and control (n = 9) groups of animals were formed. Experimental osteoporosis in rabbits of the experimental group was caused by the administration of 0.4% solution of dexamethasone (4 mg / ml) (KRKA, Slovenia) for the 21st day at a dose of 1.2 mg / kg body weight 1 time / day. Control animals were injected with saline. Blood samples for biochemical studies were taken before the induction of osteoporosis and on the 7th, 14th, 21st day. Serum levels of total calcium (Ca) and phosphorus, activity of total alkaline phosphatase and its bone isoenzyme, tartrate-resistant acid phosphatase were determined. Measurements were performed with a spectrophotometer Stat Fax 4500. X-ray examinations were performed on an X-ray machine RUM-20 before the induction of osteoporosis and on the 7th, 14th, 21st day of the study. On the 14th day of the study, some areas of the spongy substance of the proximal femur have the appearance of a large-loop pattern due to the resorption of individual bone beams. There is also an expansion of the bone marrow canal due to bone resorption, thinning and emphasizing the edges of the cortical layer. On the 21st day, changes characteristic of osteoporosis were observed - low intensity of X-ray contrast shadow of bone, significant thinning of bone structure. Radiographically established changes in bone tissue correlate with biochemical parameters of rabbit blood. On the 21st day of osteoporosis induction in experimental animals, the level of total Ca decreased 2.1 times (p <0.001), and inorganic P increased 1.8 times (p <0.001), compared with normal and control animals. The level of total alkaline phosphatase and bone isoenzyme alkaline phosphatase on the 21st day of the study exceeded the performance of clinically healthy and control animals 1.1 times (p <0.001). The activity of tartrate-resistant acid phosphatase increased dynamically and on the 14th day was 30.7 ± 0.36 units / l, which is 1.1 times (p <0.001) higher than its level in clinically healthy animals, and 21st day - 1.2 times (p <0.001), respectively. The corticosteroid model of osteoporosis causes the manifestation of its radiological signs on the 14th day after induction, accompanied by hypocalcemia, hyperphosphatemia with a decrease in Ca:P and increased activity of alkaline and tartrate-resistant acid phosphatases. The complete pathochemical phase of osteoporosis occurs on the 21st day, which is manifested by a significant decrease in the ratio of phosphatases. Key words: secondary osteoporosis, bone fractures, corticosteroids, dexamethasone, compact and spongy bone tissue, rabbits.