A case-control study was used to examine the relationships between exercise history, toe grabs and the risk of catastrophic proximal sesamoid bone fracture in racing Thoroughbreds. Researchers collected the lower limbs and shoes of 269 horses that were examined by necropsy as part of the California Horse Racing Board’s Postmortem Program and official race and timed work records were obtained from the Jockey Club. Comparisons were made between horses with and without sesamoid bone fractures.
The majority of horses (86 percent) wore some type of toe grab, with just over half (57 percent) using grabs less than or equal to 4 mm in height and 29 percent using grabs greater than 4 mm in height. Between one quarter and one third (28 percent) of horses wore pads and 15 percent had rim shoes.
Horses that sustained sesamoid fractures spent more time in active training, completed more training and racing events, had higher exercise intensity during the preceding 12 months and greater cumulative career distances compared with controls.
No significant association was detected between toe grab use and sesamoid fracture, but there was a slight tendency for increased risk of fracture with increased toe grab height.
The authors suggest the results support a link between catastrophic fracture and accumulated microdamage beyond what can be repaired through adaptation to exercise for proximal…