RUPTURE OF THE DISTAL SESAMOIDEAN LIGAMENTS OF A HORSE - VERTICAL FORCES AND TEMPORAL COMPONENTS OF THE STRIDES BEFORE, DURING AND AFTER INJURY

The temporal components and vertical forces of the strides before, dur ing and following rupture of the distal sesamoidean ligaments of the r ight forelimb were recorded from instrumented shoes. The right front h oof was shed with an instrumented shoe containing transducers located at the toe and both sides of the heel.The left front hoof was shed wit h a shoe containing a single transducer positioned over the center of the frog. The Thoroughbred mare had galloped through a track straighta way and entered the turn when the injury occurred. The horse had chang ed from a right to left lead five strides before the breakdown. In the three strides prior to the injury, no abnormalities, such as stumblin g, were observed. During the stride in which the breakdown occurred, t he right front hoof landed first on the lateral side of the heel rathe r than on the medial side as in the preceding strides. The forces on b oth sides of the heel initially increased in a normal pattern and at t he time of peak force, rupture of the distal sesamoidean ligaments app arently occurred. Following the injury, marked changes were observed i n the force-time curves which included a pronounced impact force on th e toe and very low peak forces on all transducers.