The influence of exercise during growth on ultrasonographic parameters of the superficial digital flexor tendon of young Thoroughbred horses.

This research investigates whether conditioning exercise in young thoroughbred horses influences the structure of the superficial digital flexor tendon, an essential part of the musculoskeletal system, and finds no evidence of harmful impacts.

Objective and Method

The study set out to determine if structured conditioning exercises during a young thoroughbred horse’s growth period could lead to detectable harm to the superficial digital flexor tendon (SDFT), or an increase in its cross-sectional area (CSA). The research team organized 33 thoroughbred foals into two groups: one ‘control’ group where the foals were simply allowed to roam and exercise in a pasture, and a second ‘conditioned’ group that from 21 days old underwent a conditioning exercise that involved travel over a specifically constructed grass track for 5 days a week until they reached 18 months.

• Both groups of horses were allowed to graze and exercise in a pasture.
• Regular observations and monthly orthopedic examinations were conducted for all foals.
• Ultrasonographic images of the SDFT from both forelimbs of the horses were taken when they were 5, 8, 12, 15, and 18 months old.
• The CSA was verified by analyzing digital photographs of the SDFT’s transected surface in 12 horses at 17.1 months old.

Results

The study found no evidence of tendonopathy in either study group. Moreover, the most significant growth in the tendon’s CSA in both groups happened between the ages of 5 and 8 months. Researchers did not observe any meaningful differences in the CSA between the left and right legs, or between male and female horses. There was a trend suggesting a larger CSA in the conditioned group, but this was not statistically significant.

Conclusions

The study concluded that there was no definitive evidence for adaptive hypertrophy (increase in size) of the SDFT, either due to the regimen not being intense enough or because spontaneous pasture-based exercise might already be maximizing tendon development. The researchers noted that a moderate amount of early conditioning exercise against a backdrop of continual pasture-based exercise does not disrupt the healthy development of the flexor tendon in young thoroughbred horses.