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Radiographic changes in Thoroughbred yearlings. Part 1: Prevalence at the time of the yearling sales
Article first published online: 5 JAN 2010
2003 EVJ Ltd
Equine Veterinary Journal
Volume 35, Issue 4, pages 354–365, June 2003
How to Cite
KANE, A. J., PARK, R. D., McILWRAITH, C. W., RANTANEN, N. W., MOREHEAD, J. P. and BRAMLAGE, L. R. (2003), Radiographic changes in Thoroughbred yearlings. Part 1: Prevalence at the time of the yearling sales. Equine Veterinary Journal, 35: 354–365. doi: 10.2746/042516403776014280
- Issue published online: 5 JAN 2010
- Article first published online: 5 JAN 2010
- [Paper received for publication 20.02.01; Accepted 03.07.02]
Reasons for performing study: Radiography in presale examinations of TB yearlings has become standard practice in recent years.
Objectives: To describe the prevalence and distribution of radiographic changes in the fetlocks, carpi, tarsi, stifles and fore feet of Thoroughbred yearlings in central Kentucky when these joints were examined as part of routine pre- and post sale evaluations.
Methods: Horses subjected to radiographs included the fore (n = 1127) and hind (n = 1102) fetlocks, carpi (n = 1130), tarsi (n = 1101), stifles (n = 660) and fore feet (n = 300). Radiographic changes were categorised by location and type of change present (e.g. lucency, fragment) for each series.
Results: In the fore fetlocks 1.6% had fragmentation of the proximal dorsal first phalanx and 0.5% fragmentation of the proximal palmar aspect. In the hind fetlocks 5.9% had fragmentation at the plantar aspect and 3.3% fragmentation dorsally. Lucencies, fragments or loose bodies were detected at the dorsal aspect of the distal third metacarpus in 2.8% and, at the same location on the third metatarsus, 3.2%. Most yearlings (98%) had vascular channels in the proximal sesamoid bones and irregularvascular channels (>2 mm wide or with nonparallel sides) were more common (79%) than regular vascular channels (56%). The intermediate ridge of the distal tibia was the most common location for fragmentation in the tarsus (4.4%).
Conclusions: While some radiographic changes, e.g. vascular channels in proximal sesamoid bones, are very common in Thoroughbred yearlings, others, e.g. fragmentation or subchondral lucency within joints are quite rare usually affecting less than 5% of the population.
Potential relevance: Veterinarians should expect to find radiographic changes in Thoroughbreds presented for examination prior to the yearling sales. The rarity of some changes thought to affect soundness or racing performance will make further invesigation of these conditions in horses without clinical signs more difficult.