Abstract :
Developmental orthopaedic disease (DOD) affects all breeds and is a common cause of pain and lameness for horses in sports.
A thorough knowledge of between-breed variations for the prevalence of DOD, for its distribution among the various joints and
for its severity at earlier stages in the disease process is needed in order to improve the relevance and the cost-effectiveness of
DOD screening protocols. However, no prevalence study for DOD simultaneously performed on several breeds with similar farming
systems and based on radiographic findings (RF) on quite a large number of joints and views, has been reported earlier. The
objective of this study was to describe variations in the prevalence, location and severity of DOD in foals at weaning among
Warmbloods (Wb), Standardbreds (St) and Thoroughbreds (Tb) with similar farming systems. DOD assessment was based on RF on
the limb joints. A total of 392 foals from 21 volunteer stud farmers were included. To determine the statuses of foals regarding
DOD, they were X-rayed on the front- and hind-limb digit, carpus, hock and stifle joints. X-ray data were analysed by three
experienced equine veterinarians who gave a common assessment about the entity and the severity of RF. Between-breed variations
were analysed in two steps: the first implemented for each anatomical site; the second considered only foals affected by DOD to
explore RF association patterns on the affected sites, at foal level. The three breeds were represented by 25.0% of Wb, 41.1% of
St and 33.9% of Tb. DOD was present in 66.3% of the foals (95% confidence interval (CI)561.6% to 71.0%). Prevalence of foals
affected by DOD and distribution of the RF severity score on the anatomical sites differed depending on the breed: Wb foals
seemed to be the most affected by DOD. Cluster analyses showed no clear association among sites. However, Wb and Tb foals
were preferentially classified together because they were affected on the same sites, whereas St foals were distributed in other
classes. The most severely affected sites were the proximal part of the hock and the femoro-patellar joint for Wb and St foals,
and the fore fetlock and the distal part of the hock for Tb foals. This is the first epidemiological study reporting between-breed
variations in DOD distribution and severity, for the limb joints of foals. These results contribute to broaden the knowledge on
DOD and are of great interest to improve detection of DOD within a particular breed.
Keywords :
breeds , Horses , osteochondrosis , Prevalence , Radiography
