Referral of the lameness case for standing magnetic resonance imaging

Abstract

Standing magnetic resonance imaging (MRI) using a 0.27 Tesla Hallmarq low-field permanent magnet, custom designed for the equid, has an established role in the lameness investigation in the horse and has become widely available. Prior to a referral, horses must undergo a thorough lameness investigation and the source of lameness must be isolated to a well-defined area, as only a small area of the horse (for example the foot) is imaged on each scan. However, we now know there are substantial limitations to the accuracy of equine nerve blocks and this needs to be taken into consideration, with possible scans of additional areas being performed. Additionally, MRI is not suitable to achieve a complete diagnosis for multi-limb lameness unless multiple scans (of all affected limbs) are performed. It is important to discuss with the client beforehand the limitations of MRI and costs involved, in addition to the advantages of MRI. A detailed history for the clinician interpreting the MRI is essential to be able to give clinically useful recommendations. This article does not aim to give a complete overview of lameness and MRI, but rather to clarify why a thorough work up is so important, and the explain to basics of this imaging modality, as well as what can be expected by the referring veterinary surgeon.