INFORMATION FOR OWNERS OF HORSES HAVING MRI
MRI (magnetic resonance imaging) is a diagnostic imaging technique that involves placing the part of the body to be imaged inside a strong magnetic field. Pulses of radio waves are applied to the area, and a signal (also in the form of radio waves) is received by a computer which generates the image.

MRI is a relatively new technique in equine medicine. At Bell Equine Veterinary Clinic we have a MRI scanner that can be used to image the lower leg area (from foot to knee or hock) of standing horses. Our clinic was the first veterinary clinic in the world to use this technology (the first scanner was installed in 2002, and has since been upgraded). Prior to this, MRI could only be undertaken in horses at a few centres around the world using human MRI scanners. The standing equine MRI scanner has considerable advantages over more conventional human MRI scanners, which require the horse to be placed under general anaesthesia. Our clinic has played a central role in developing this technology for clinical use in horses, and we have acquired unrivalled expertise in this area.

The standing equine MRI scanner is a low field (0.27 Tesla) scanner. Horses are scanned standing under sedation. The front shoes need to be removed (or the hind shoes if the hind legs are being scanned). The entire scanning procedure may take between 1 to 3 hours, depending on the area being scanned and the temperament of the horse. As far as it is known, the procedure is safe and it does not involve exposure to any form of ionising radiation (unlike radiography, CT scanning and nuclear scintigraphy).

MRI allows evaluation of both bone and soft tissues at the same time. The technique has specific indications for the evaluation of certain types of lameness in horses, and the area being scanned must be localised (usually by means of nerve blocks) prior to having the MRI performed. One of the most useful indications for standing MRI is in the evaluation of horses with lameness originating inside the foot. Our experience has shown that many horses with chronic lameness affecting either one or both front feet have a variety of soft tissue injuries (such as damage to the deep digital flexor tendon or one of the many ligaments in the foot); these injuries cannot be accurately diagnosed using more conventional techniques. MRI is also very accurate in diagnosing bone diseases (including early navicular disease and pedal bone diseases) that are difficult to diagnose in any other way. MRI also has many applications in evaluating other diseases in the lower legs, and our knowledge concerning its value is expanding all the time.