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27-09-2011 | Article

MRI uncovers carpus, proximal metacarpal lesions among lame horses


Free abstract

MedWire News: Study findings show that magnetic resonance imaging (MRI) is an effective diagnostic modality for detecting a variety of lesions in the carpus and proximal metacarpal region in horses, which are often responsible for pain that causes lameness.

"This study showed a different and wider range of MRI abnormalities in the carpus and proximal metacarpal region of horses of different work disciplines compared with previous descriptions," say Annamaria Nagy (Centre for Equine Studies, Newmarket, Suffolk, UK) and co-authors.

For the study, the researchers reviewed the clinical records of 50 horses that underwent MRI of the carpus and/or proximal metacarpal region at the Animal Health Trust in Newmarket during 2003-2010. MRIs of all horses and available radiographs, and ultrasonographic and scintigraphic images were assessed. MRI findings were compared with results of other diagnostic imaging techniques when possible.

In total, 72 MRI studies of 58 limbs were performed among horses from a broad range of work disciplines and across a range of different ages (2-17 years; aged on average 6.8 years). Unilateral forelimb lameness was present among 41 horses, with nine horses showing bilateral lameness. Overall, duration of lameness ranged from 1 week to 2 years, averaging at 3.4 months.

The most commonly detected primary abnormality was reduced signal intensity in the T1- and T2-weighted images in the medial aspect of the carpus and the proximomedial aspect of the metacarpal bones, which was seen in 29 limbs.

Nine limbs presented primary abnormalities in the adjacent aspects of the second and third metacarpal bone (McII and McIII, respectively). These included thickening of the cortex and decreased signal intensity of the medulla, periosteal and endosteal irregularity, osteophyte formation on the adjacent surface of the McII or the McII, and loss of fiber structure and increased signal intensity within the medial interosseous ligament consistent with syndesmopathy.

Furthermore, six limbs showed primary abnormalities of the palmar cortex of the McIII, including thickening of the cortex, endosteal irregularity, and areas of increased signal intensity in the cortex.

Significant abnormalities of the suspensory ligament (SL) with associated lesions in the adjacent palmar cortex of the McIII were seen in four limbs. A further four limbs showed ligament and associated osseous abnormalities between the second and third carpal bones and the McII and McIII.

The authors note that the majority of abnormalities were identified in the medial aspect of the carpus and proximal metacarpal region, suggesting that "the medial aspect of the carpus and proximal metacarpal region may be exposed to greater biomechanical forces than laterally," say the researchers.

They add that lameness originating from the carpus has been traditionally seen in race horses, but the current study revealed a high number of osseous abnormalities among horses of various work disciplines.

"MRI has the potential to give additional diagnostic information compared with conventional imaging techniques," conclude the authors in the Equine Veterinary Journal.

By Ingrid Grasmo