Clinical relevance of radiographic findings in proximal sesamoid bones of two-year-old standardbreds in their first year of race training.

This study aimed to classify and understand the association between radiographic findings of proximal sesamoid bone lesions in Standardbred racehorses, and the clinical signs of these diseases. 71 horses were monitored, with radiographs taken at three-month intervals. The findings showed different categories of lesions, with varying degrees of clinical relevance and association with lameness.

Methodology

• The study involved taking radiographs of all four fetlocks of 71 Standardbred racehorses every three months for one year.
• Findings on the abaxial surface of the proximal sesamoid bones were categorized into three types according to the severity of lesions.
• A correlation was then made with clinical findings at the time of examination.

Results

• Type-1 lesions, which were characterized by one or two linear defects with a width of <= 1mm, were found in 55% of the horses at the beginning of the training. These horses didn't show clinical signs of disease, and the lesions were not considered to be clinically relevant.
• Type-2 lesions, characterized by three or more linear defects with a width of <= 1mm, were found more frequently after three months of training. Although not manifesting clinical signs of disease, 66% of horses that had diseases of the suspensory apparatus had this type of lesion. When lameness was observed, it was linked with the soft tissue problem and the changes in the sesamoid bones were regarded as secondary.
• Type-3 lesions were abnormally wide and shaped linear defects. They were found in 7 horses at the start of the study and remained consistent throughout the study. These were linked with lameness during training and were considered to be clinically relevant and suggestive of primary sesamoiditis.

Conclusions

• The study concluded that the severity and type of lesions on the proximal sesamoid bones in racehorses vary in clinical relevance.
• The type-3 lesions, especially, were considered a primary sign of a condition called sesamoiditis due to their consistent association with lameness throughout the study.