Third metacarpal bone laterality asymmetry and midshaft dimensions in Thoroughbred racehorses.
Abstract: 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. Methods: An observational study. Methods: 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). Conclusions: 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.
Publication Date: 2005-05-24 PubMed ID: 15907042DOI: 10.1111/j.1751-0813.2005.tb11657.xGoogle Scholar: Lookup
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Summary
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The study aims to understand the relationship between the length of a racehorse’s third metacarpal bones (MC3), commonly known as shin bones, and the thickness of their dorsal cortices or outer layer of bone. This research also explores if there’s a correlation between the size differences of the two MC3 bones in individual horses and variation in the thickness of the dorsal cortex.
Objective and Study Sample
- The study is based on Thoroughbred racehorses that maintain similar maximum running speeds. The objective is to determine if horses with longer MC3 bones also have thicker dorsal cortices.
- Additionally, the research investigates whether horses showcasing larger differences in the length of their right and left MC3 bones have significant variations in the thickness of the dorsal cortex in both limbs.
- A group of 40 Thoroughbred racehorses, aged between 2 to 6 years and in active racing training at two stables, were selected for the study.
Methods and Measurements
- Standardized procedures were used to measure the bone length and dorsal cortical width from two sets of radiographs for each horse’s left and right metacarpus.
Results
- Results indicated a linear relationship between dorsal cortex thickness and bone length for lengths between 25 and 30 cm for both the right (R2 = 0.30, P = 0.0003) and the left MC3 bones (R2 = 0.23, P = 0.002).
- In essence, longer bones were found to have thicker dorsal cortices.
- However, when comparing the thickness of the dorsal cortex and bone length within individual horses, the study found no consistent relationship (R2 = 0.008, P = 0.58).
Conclusions
- The study concluded that racehorses with longer MC3 bones are likely subjected to a greater dorsopalmar bending moment at the mid-shaft, resulting in a thicker dorsal cortex.
- However, the lack of a relationship between midshaft thickness and bone length in individual horses suggests that direct mechanical effects of body structure and environment are less critical than the horse’s skill level or the degree of their lateral movements, developed prior to exposure to fast exercise.
- The research also suggests that horses with longer right MC3 bones might better control the load on the right MC3 during fast exercise.
Cite This Article
APA
Davies HM, Watson KM.
(2005).
Third metacarpal bone laterality asymmetry and midshaft dimensions in Thoroughbred racehorses.
Aust Vet J, 83(4), 224-226.
https://doi.org/10.1111/j.1751-0813.2005.tb11657.x Publication
Researcher Affiliations
- Department of Veterinary Science, University of Melbourne, Parkville, Victoria 3010. h.davies@unimelb.edu.au
MeSH Terms
- Animals
- Forelimb / anatomy & histology
- Forelimb / diagnostic imaging
- Forelimb / physiology
- Horses / anatomy & histology
- Horses / physiology
- Locomotion
- Metacarpus / anatomy & histology
- Metacarpus / diagnostic imaging
- Metacarpus / physiology
- Physical Conditioning, Animal / physiology
- Radiography
Citations
This article has been cited 3 times.- Paśko S, Dzierzęcka M, Purzyc H, Charuta A, Barszcz K, Bartyzel BJ, Komosa M. The Osteometry of Equine Third Phalanx by the Use of Three-Dimensional Scanning: New Measurement Possibilities. Scanning 2017;2017:1378947.
- Dzierzęcka M, Charuta A. The analysis of densitometric and geometric parameters of bilateral proximal phalanges in horses with the use of peripheral quantitative computed tompgraphy. Acta Vet Scand 2012 Jul 13;54(1):41.
- Son JK, De Paz P, Kim J, Sanaei R, Ryu S, Bailey S, Davies HMS. The change in third metacarpal mid-diaphyseal radiographic dimensions in Thoroughbred foals through growth. Equine Vet J 2025 Nov;57(6):1600-1611.
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