Femoral asymmetry in the Thoroughbred racehorse.
OBJECTIVE
To investigate the occurrence of geometrical asymmetries in the macro-architecture of left and right femurs from Thoroughbred racehorses previously used in competitive training and racing in New South Wales, Australia.


METHODS
Detailed postmortem measurements were made of 37 characteristics of left and right femurs from eleven Thoroughbred racehorses euthanased for reasons unrelated to the study. Measurements focused on articulating surfaces and sites of attachment of muscles and ligaments known to be associated with hindlimb locomotion.


RESULTS
Five measurements were significantly larger in left compared to right femurs (P < 0.05). The regions showing significant differences between left and right limbs were proximal cranial and overhead medio-lateral widths, greater trochanter depth, depth of the fovea in the femoral head and distal inter-epicondylar width.


CONCLUSIONS
The left-right differences in femoral morphology were associated with sites of muscle and ligament attachment known to be involved with hindlimb function in negotiating turns. These differences may be the result of selection pressure for racing performance on curved race tracks and/or adaptations related to asymmetrical loading of the outside hindlimb associated with repeated negotiation of turns on such tracks.
Pearce
G P
GP
Faculty of Rural Management, University of Sydney, Leeds Parade, Orange, New South Wales 2800. gpp28@cam.ac.uk
May-Davis
S
S
Greaves
D
D
D000818:Animals; D012090:Cumulative Trauma Disorders / Q000473:pathology / Q000662:veterinary*; D005269:Femur / Q000473:pathology*; D006734:Horse Diseases / Q000473:pathology* / Q000503:physiopathology; D006736:Horses; D008124:Locomotion; D010805:Physical Conditioning, Animal / Q000502:physiology*