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Abstract

Lameness from fetlock and pastern regions is a big challenge to most equine practitioners and produces a detrimental effect on horses’ activity and on owners’ finances. Nuclear scintigraphy, radiography and ultrasonography are not conclusive when assessing of fetlock and pastern lameness. This study describes the magnetic resonance imaging (MRI) features in 30 draft horses with chronic, un-treated lameness attributable to fetlock and pastern regions as well as confirms these features by postmortem examination. Thirty-three cadaver limbs were collected after euthanasia, imaged by MR and lastly examined grossly. Seventeen lesions were recorded and described using MRI. MRI revealed injuries of both soft and osseous tissues in 24 horses (80%), soft tissue injuries in five horses (16.7%) and bone and cartilage injuries in one horse (3.3%). All horses had multiple MRI abnormalities. The most frequent MR lesions were digital tenosynovitis (n=13), straight sesamoidean desmitis (n=10), osteosclerosis in the distal part of third metacarpal bone (MCIII) or first phalanx (PI, n=10), adhesions between straight sesamoidean ligament (SSL) and deep digital flexor tendon (DDFT, n=9), oblique sesamoidean desmitis (n=7), cartilage erosions of fetlock or pastern joints (n=7), adhesions between proximal digital annular ligament and DDFT (n=6), DDFTendinitis at pre-navicular part (n=6), proximal digital annular desmitis (n=5), subchondral bone cyst of PI (n=3), and cyst like lesions in PI and PII (n=2). In conclusion, MRI played a pivotal role in comprehensive evaluation of fetlock and pastern regions and it is highly recommended for examination of all structures of fetlock and/or pastern regions in chronically lame draft horses.