Forelimb skeletal scintigraphy responses in previously untrained Thoroughbreds undergoing initial treadmill training

Area of Science:

• Equine Sports Medicine
• Diagnostic Imaging
• Skeletal Physiology

Background:

• Scintigraphy is a diagnostic tool used to investigate lameness in horses.
• Previous studies have not prospectively monitored skeletal responses in groups of racehorses undergoing training.
• Understanding training-induced skeletal changes is crucial for preventing injuries in Thoroughbreds.

Purpose of the Study:

• To prospectively evaluate skeletal responses in Thoroughbred racehorses during initial treadmill training using scintigraphy.
• To test the hypothesis that training increases radiopharmaceutical uptake in high-motion joints and the dorsal third metacarpal bone (MC3).

Main Methods:

• Eight untrained Thoroughbred horses underwent 9 weeks of daily inclined treadmill exercise.
• Skeletal scintigraphy with 99m Technetium-methylene diphosphonate was performed at baseline and Weeks 3, 6, and 9.
• Radiopharmaceutical uptake in forelimb joints and MC3 was graded by blinded investigators; data analyzed using Mann-Whitney Rank Sum Test (P<0.05).

Main Results:

• Significant increases in radiopharmaceutical uptake were observed in the carpus (P=0.031), metacarpophalangeal joint (P=0.021), proximal phalanx (P=0.035), and distal phalanx (P=0.003) after training.
• No significant change in radiopharmaceutical uptake was detected in the dorsal third metacarpal bone (P>0.05).
• These findings suggest dynamic skeletal adaptation in response to training stress.

Conclusions:

• Initial treadmill training induces significant skeletal adaptation in Thoroughbred racehorses, particularly in high-motion joints.
• The dorsal third metacarpal bone shows less response to this specific training protocol.
• Scintigraphy is a valuable tool for monitoring training-induced skeletal changes and potentially identifying early signs of stress or injury.