Understanding metaphysis biology: Effects of training and age on bone parameters of the third metatarsus in Thoroughbred horses

Abstract

Aim: to obtain more information about how the metaphyseal region in the horse develops during early life and what influence initial training for racing has on the growth and development of the metaphysis. Methods: Graphs of the parameters Bone Mineral Content (BMC), Bone Area (BA) and Volumetric Bone Mineral Density (BMDv) of the third metatarsal (Mt3)bone of trained and untrained 2-year old Thoroughbred horses were compared. In these graphs, slices at increasing distances from the metaphyseal growth plate were compared between the two groups. This way of imaging allowed to compare the whole metaphyseal area between individuals instead of comparing only specific measuring points. To study the development of the physis near the time of birth, the metaphyseal profiles of still-born foals were studied and compared with those of the 2 year old horses. Results: The metaphyseal region of Mt3 responded in the medium exercise intensity subgroup by making a denser cortex not a denser trabecular area, no response in BMC and BA was measured. The high intensity exercise subgroup responded on the given exercise by increasing trabecular and cortical BMC, trabecular and cortical area and cortical BMDv. The metaphyseal region in the foals was different in all parameters measured compared to that of 2 year old horses. Conclusions: it is possible to compare trained and untrained horses by comparing graphs that plot BMC, BA or BMDv against distance from the growth plate. The metaphyseal profile was suitable in comparing the different parameters of foals and 2 year old horses.