Speed of sound measurements of the third metacarpal bone in young exercising thoroughbred racehorses.

The study investigates how factors like exercise, age, and gender affect cortical bone in the metacarpal bone of young Thoroughbred racehorses. The researchers used a technique to measure speed of sound (SOS) values in the bone during a nine-month exercise period.

Methodology

• The longitudinal study involved 75 racehorses between 2 to 4 years old. Their third metacarpal bone (MC III), located in their front legs, was monitored over nine months, during which they underwent physical training.
• SOS measurements were made in 5 to 7 week intervals during the exercise period, with the application of an axial transmission technique.
• The horses’ medical data and training programmes, involving slow gallop, canter and high-speed work, were duly recorded.
• For 2-year-old horses, these SOS measurements commenced before they started high-speed training.

Findings

• The SOS values were found to be significantly lower at the dorsal (back) side of MC III compared to measurements taken at the lateral (side) and the medial (middle) aspect of the same bone.
• SOS values were seen to decrease as the number of measurement cycles increased.
• Upon repeating measurements at cycles 2, 3 and 4, considerable differences emerged in SOS values at the dorsal MC III.
• With rising age, SOS values registered at the lateral and medial aspects of MC III showed an increasing trend.
• However, as age increased, there was a falling trend in SOS values at the dorsal aspect of MC III.
• Mares exhibited higher SOS values at the dorsal aspect of MC III, compared to stallions.
• In 2-year-old Thoroughbreds, significant differences were observed in dorsal MC III SOS values between distinct measurement cycles. Similar differences were displayed by 3-year-old horses between cycles 3 and 4.
• The data indicated no significant influence from the intensity of training on SOS values.

Conclusion

• These results demonstrate that the SOS values of MC III in young exercising Thoroughbred racehorses fluctuate depending on age, gender and measurement cycle.
• This suggests that these factors lead to adaptations in the superficial cortical bone properties of MC III in such horses – changes that are most likely aimed at improving performance or ensuring long-term skeletal health.