Use of standing low-field magnetic resonance imaging to assess oblique distal sesamoidean ligament desmitis in three Thoroughbred racehorses.

Abstract

Desmitis of the oblique distal sesamoidean ligaments (ODSL) is caused by hyperextension of the metacarpophalangeal/metatarsophalangeal joint and has been described as a significant cause of lameness in racehorses. In this study, three Thoroughbred racehorses (age range: 3–6 years) were diagnosed with desmitis of the forelimb ODSL using standing low-field magnetic resonance imaging (sMRI). Radiography and ultrasonography were inconclusive with regard to a definitive diagnosis. For all horses, the sMRI characteristics included increased signal intensity within the medial ODSL on T1-weighted gradient echo, T2-weighted fast spin echo and short tau inversion recovery fast spin echo images, which use a fat suppression technique. Effusion of the digital flexor tendon sheath was also clearly visible on sMRI. Following rest and controlled exercise for roughly 3 months, two horses successfully returned to racing within 5 months. Our findings support the use of sMRI for diagnosing ODSL injuries in Thoroughbred racehorses.