Radiographic evaluation of changes in the proximal phalanx of Thoroughbreds in race training.

The research examines the changes in the bone structure of the proximal phalanx in the fore-limbs of racing Thoroughbreds due to exercise and racing, and undersigns the distinct biomechanical impact of training and exercise on this part of the horse’s anatomy.

Research Methodology

• The study utilized twenty-seven 2-year-old Thoroughbreds including 20 females, 2 males, and 5 geldings.
• These horses were mainly in training for straight-line races and clockwise direction races.
• For comparison, the research team took radiographic images, i.e., X-rays of the metacarpophalangeal joint of the horses – before they started training and a year after.
• Detailed measurements of the different parts of the bone, such as the dorsal, palmar, lateral, and medial cortex, and the medulla were done, focusing more on the ratios as opposed to absolute values to negate differences in bone size among different horses.
• During the course of the research, they lost 10 horses and successfully obtained radiographs for 17 horses after a year. Out of these, 9 raced in a clockwise direction, while 8 raced in both clockwise and counter-clockwise directions.

Key Findings

The results showed that in the span of a year, the horses’ training led to a change in their anatomy. Specifically, the palmar cortex in the right forelimb became significantly thicker compared to that in the left forelimb.
• It was found that there were no differences in the bones of the right and left forelimbs at the start of the research.

Conclusion and Implication

• The study suggests that the patterns of strain or stress, the biomechanics of rapid exercise and the specifics of the training regime are likely factors determining the adaptive responses in the proximal phalanx.
• The change in bone structure offers insights into understanding weight-bearing distribution along the proximal phalanx, and also gives way to evaluate the relationship between exercise and bone remodeling in this part of a horse’s anatomy.