Cinematographic analysis of the gait of lame horses II: Chronic sesamoiditis

The gait characteristics of a horse with chronic sesamoiditis of the left forelimb are described. On physical examination the affected metacarpophalangeal joint was foundto be enlarged. Extensive fibrosis on the palmar surface of the proximal sesamoid bones and in the suspensory ligament resulted in a reduced range of movement in the joint At rest the horsepointed the left toe and was reluctant to bear weight on that limb. Observation at the trot revealed an obvious head nod on the sound right diagonal. During the left diagonal stance phasethe head and neck were raised, the LF fetlock was held in a rigid upright position, and hyperextension of the joint was restricted.

Cinematographic analysis showed that the LF had a longer stance phase than the RF, due to anincreased anterior phase combined with a slower breakover (p<0.01). At the end of its stance phase the LF overlapped with both the RF and LH, so there was no left suspension. The rightdiagonal stance phase was followed by a short suspension before impact of the LF. With regard to linear measurements the horse took a longer step from the RF to LF and from the RH to LHthan for the contralateral pairs (p<0.01). As a result the distance between the RF and LH inthe right diagonal stance phase was significantly less than that between the LF and RH in the left diagonal stance phase (p<0.01).

Kinematic analysis showed that the sound RF made flat foot impact with the ground, whereas, at the end of the swing phase, the LF toe flipped up and impact was heel first The neck was elevated during the early part of the LF stance phase, until the limb had passed the midstance position when the poll fell, reaching its lowest level at the RF midstance position. Author's address: Department of Veterinary Anatomy, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan.