Reasons for performing study
The distribution of lesions detected using magnetic resonance imaging (MRI) of hind feet has not been reported.
To evaluate type and distribution of lesions detected using MRI in hind feet of lame horses and to compare the findings with those reported in front feet; to document follow-up information.
Horses were selected if hindlimb lameness was abolished by plantar nerve blocks performed at the base of the proximal sesamoid bones. Magnetic resonance images were acquired using either a low-field or a high-field magnet, and all images were evaluated retrospectively by both authors. A primary diagnosis was defined as the most likely cause of lameness, based also on clinical findings and results of other imaging techniques. If ≥3 structures were equally affected, the horse was classified as having multiple injuries. Follow-up information was collected by telephone questionnaire; outcome was classified as return to former level of athletic function, working at a lower level or retired.
Thirty-eight horses were included. Primary collateral sesamoidean ligament (CSL) injury was identified in 9 horses. Nine horses had multiple injuries, 8 had primary bone pathology, 5 had collateral desmopathy of the distal interphalangeal joint, one had primary deep digital flexor tendonitis, 2 had navicular bone pathology and 4 had lesions involving other structures within the foot. Seven horses were subjected to euthanasia shortly after diagnosis; 6 as a result of poor prognosis and one as a result of post anaesthetic complications, 4 of which had primary bone lesions, 2 multiple lesions and one distal interphalangeal joint pathology. Follow-up information was available for 24 horses. Eleven horses returned to previous performance and 2 to a lower level of performance; 9 horses were retired because of recurrent lameness. Five of 8 horses with CSL injury returned to previous performance and 2 to a lower level.
Conclusions and potential relevance
Collateral sesamoidean ligament injury and primary bone pathology are commonly observed on MRI examination of hind feet, and the prognosis is reasonable.