Density and geometry of the third metacarpal in juvenile racehorses treated with exogenous equine somatotropin
Year: 2005
Type: dissertation
Abstract: The effect of exogenous somatotropin (eST) on bone changes were evaluated in\ntwenty-nine juvenile horses in race training using radiographs of the third metacarpal\nobtained over the course of a 128 day research project. A biodensitometer was used to\nmeasure bone density, and a micrometer was used to measure cortical bone width and\nmedullary cavity width. Fifteen horses were given daily intramuscular injections of eST\nand fourteen horses were given daily intramuscular injections of sterile saline and served\nas the control group.\nBy day 128, the increase in total radiographic bone aluminum equivalence (RBAE)\nwas significantly greater in the eST horses than in the control horses. The increases in\nRBAE in the dorsal and the medial cortices were greater in the eST horses than in the\ncontrol horses, but these differences were not significant. There was a trend for changes\nin the ratio of RBAE in the dorsal to palmar and in the medial to lateral cortices to be\ngreater in the eST than in the control horses.\nBy day 128, the increases in both the dorsal and the medial cortical bone width were\nsignificantly greater in the eST than in the control group of horses. The eST horses had a\nsignificantly greater decrease in dorsal to palmar medullary cavity width, and increase in\ndorsal to palmar bone diameter than the control group. A computed index of dorsal\ncortical bone increased significantly more in the eST than in the control group.\nThe stresses applied to bone are greater in the dorso-medial direction in racehorses.\nTo decrease the strain, bone must either increase in bone mineral density, cortical width,\nand/or bone diameter. Both the eST group and the control group did make these changes in bone over time, but the eST group more effectively remodeled and modeled bone to\nincrease the strength of the third metacarpal than did the control group of horses.\nIn this research project, exogenous somatotropin treatment had a positive effect on the\ndensity and geometry of the third metacarpal. These changes are believed to result in a\ndecreased risk of bone injury to the eST treated horses.
Author: K.L. Thomson
Language: English
Subfield: Equine
Field: Veterinary
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2727961995