Document Detail

Third metacarpal bone laterality asymmetry and midshaft dimensions in Thoroughbred racehorses.
MedLine Citation:
PMID:  15907042     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: The aims of this study were to test whether longer third metacarpal (MC3) bones had thicker dorsal cortices in a group of racehorses that were exercising at similar maximum speeds, and to establish if horses with larger differences in length between their right and left MC3 bones showed larger differences in the dorsal cortical thickness between the two limbs. DESIGN: An observational study. PROCEDURE: Forty Thoroughbred racehorses aged between 2 and 6 years and in training at racing speed at two racing stables were used. Two sets of radiographs of each left and right metacarpus of each horse were measured for bone length and dorsal cortical width according to standardised methods. RESULTS: The dorsal cortex thickness showed a linear relationship with bone length for the range of lengths between 25 and 30 cm for both the right MC3 (R2 = 0.30, P = 0.0003) and the left (R2 = 0.23, P = 0.002). The longer bones had thicker dorsal cortices. When results from the two limbs were combined to test if the difference in length between the right and left MC3 in an individual horse was associated with a thicker dorsal cortex in the longer MC3 there was no consistent relationship (R2 = 0.008, P = 0.58). CONCLUSION: In this sample of racehorses longer MC3 bones were likely to have been exposed to a greater dorsopalmar bending moment at the mid shaft that was reflected in a thicker dorsal cortex. The lack of a relationship between midshaft thickness and bone length within individual horses suggests that direct mechanical effects of conformation and environment were less important than the individual's level of skill (or the degree of laterality in their movements) developed before their exposure to fast exercise. It is likely that racehorses with longer right MC3 bones were more able to control the loading of the right MC3 than the left during fast exercise.
H M S Davies; K M Watson
Publication Detail:
Type:  Evaluation Studies; Journal Article    
Journal Detail:
Title:  Australian veterinary journal     Volume:  83     ISSN:  0005-0423     ISO Abbreviation:  Aust. Vet. J.     Publication Date:  2005 Apr 
Date Detail:
Created Date:  2005-05-23     Completed Date:  2005-06-09     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0370616     Medline TA:  Aust Vet J     Country:  Australia    
Other Details:
Languages:  eng     Pagination:  224-6     Citation Subset:  IM    
Department of Veterinary Science, University of Melbourne, Parkville, Victoria 3010.
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MeSH Terms
Forelimb / anatomy & histology,  physiology,  radiography
Horses / anatomy & histology*,  physiology*
Metacarpus / anatomy & histology*,  physiology*,  radiography
Physical Conditioning, Animal / physiology*

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