Jonathan McLellan

Dr McLellan graduated with honors from the University of Glasgow (UK) Veterinary School and undertook a surgical internship in Ocala, FL, USA. He is the author of multiple peer-reviewed research articles and continues to pursue his research interests, specifically training-related injuries and rehabilitation. He is a diplomate of the American College of Veterinary Sports Medicine and Rehabilitation and an RCVS recognized Specialist in equine sports medicine. He has a special interest in challenging lameness diagnostics and the rehabilitation of sports-injuries. Along with his wife, Dr Sarah Plevin, they pioneered the introduction of UTC ultrasound to the USA, after performing extensive self-funded research using the modality.  Dr McLellan’s practice currently specialises exclusively in sports medicine referrals and UTC imaging throughout the USA and UK.

How can we use Diagnostic Imaging to Prevent Injury In the Racehorse?

Jonathan McLellan BVMS (hons) MRCVS DACVSMR RCVS Specialist (Eq Sports Med)

Musculoskeletal injury in the racehorse can be career, or even life-ending for the horse and presents significant risk to the jockey.  Research suggests many of these injuries are the result of cyclical fatigue failure in the racehorse rather than an unfortunate ‘bad step’ as was often purported to be the case.  Many injuries have a prodromal phase which may lend itself to identification by modern imaging techniques prior to clinical injury.  Such early identification also reduces the morbidity and lost training days in horses suffering non-catastrophic injuries.  It is important, however, to understand the goals and limitations when screening the non-lame horse for prodromal injuries.  The public perception is that screening should be capable of identifying all cases which are at risk of injury and while the evolution of several modern modalities has increased the sensitivity and specificity for disease detection, the ‘perfect’ test does not yet exist.  Traditional radiographs, ultrasounds and 2D nuclear scintigraphy have recently been augmented by multi-planar modalities such as CT, MRI, PET and UTC (ultrasound), in addition to wearable devices which objectively monitor movement symmetry and other measurable markers of subtle lameness.  Some of these tests have physical, financial, or regulatory impracticalities which must be considered.  The imaging results, moreover, cannot be interpreted in isolation: the clinician must ultimately possess the skill and experience to relate the imaging findings to the case-presentation and signalment to increase the likelihood of correctly identifying horses genuinely at risk of impending musculoskeletal injury.

 

Management of Subchondral Injuries in racehorses

Jonathan McLellan BVMS (hons) MRCVS DACVSMR RCVS Specialist (Eq Sports Med)

Subchondral injuries are a common source of lameness in the racehorse.  The subchondral unit bridges the articular cartilage and the trabecular bone.  Its function is to support the cartilage and dissipate force from the joint to the trabecular bone.  Damage can be developmental or traumatic, for example, in cases of subchondral bone cysts (SCBC) or, in the training racehorse, disease can be brought about by a maladaptive response to cyclical fatigue with both mechanical and vascular factors influencing the development of pathology.   In disease, there is considerable ‘cross-talk’ between the subchondral unit and the overlying hyaline cartilage, thus many cases may present with joint-related clinical signs, but this is variable.  The fetlock and carpus are common predilection sites and a range of diagnoses may exist including stress remodeling, palmar osteochondral disease, osteochondral fragmentation, and fractures.  Accurate diagnosis of subchondral disease is vital to appropriate rehabilitation and radiography, nuclear medicine (scintigraphy, PET), CT, and MRI are commonly used to support the findings of a thorough lameness examination.  The prognosis varies with the location, duration and progression of disease, and number of joint(s) affected.  Treatment may be medical or, in some cases, surgical but, in all cases, frank discussions with owners/ trainers at the outset is important to set expectations because not all cases will return to previous levels of competition.  Appropriate training and the use of adjunct modalities during rehabilitation may improve the prognosis and a thorough understanding of any given modality is incumbent on the veterinarian prior to embarking on treatment, as each treatment has a risk/ reward profile to consider.