Ultrasound screening protocol for osteochondrosis at selected predilection sites in thoroughbred yearlings

Osteochondrosis is a common condition of young horses where there is a failure of endochondral ossification, usually at predisposed sites. The estimated prevalence of osteochondrosis is 33-44%, with radiographic screening of yearlings being used to identify lesions. Radiography has two major limitations: poor sensitivity in detecting cartilaginous lesions and secondly, the exposure of the horse and personnel to ionising radiation. Ultrasonography allows imaging of the articular cartilage and subchondral bone margins and has been shown to be more sensitive in identifying osteochondrosis lesions. However, the ultrasonographic technique for examining joints is operator dependant, resulting in highly variable examinations, thus affecting its reliability and reproducibility as a screening test.

A prospective observational clinical population study was undertaken involving twenty-two clinically normal weanling thoroughbred horses on-farm, describing a detailed protocol of the ultrasonographic examination technique for on-farm screening of common sites of osteochondral disease in the young horse, namely the carpal, metacarpophalangeal, stifle, tarsal and metatarsophalangeal joints.

Two veterinary practitioners used the technique to illustrate the repeatability of the protocol. The step-by-step protocol provides a valuable, reliable, repeatable technique for veterinary professionals performing screening ultrasound in the field.