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Diagnosing Sidebone



Dr. Susan Dyson and Laura E. Jones recently published a paper in which a new radiographic view of the foot was used on 386 feet belonging to 271 horses. The objective of this study was to describe, in detail, the appearance on radiographs of ossified ungular cartilages (“sidebone”) and to evaluate the usefulness of this particular view (a flexed oblique view of the foot) to evaluate the ungular cartilages themselves. The ungular cartilages of each horse were graded on a scale of 0-5 (0 being normal and 5 being the most severe), and the shape documented (straight vs. curved). The radiographic view in which the abnormalities were best identified was also documented.


Fractures were seen most commonly in those ungular cartilages which had been graded a 4 or 5 and were best seen in this flexed oblique view. It was also shown that those feet whose ungular cartilages had these higher grades were also more likely to show other boney changes. The authors concluded that extensive ossification of the ungular cartilages, as well as an abnormal curvature, were risk factors for boney change. “Flexed oblique images provided clinically useful information including abnormal shape and fractures that may not be evident on other currently recommended images.”


It is not uncommon for Friesian horses to have “sidebone” that is found when the feet are radiographed, either due to lameness or even as part of a prepurchase examination. The extent to which “sidebone” contributes to lameness has been difficult to determine. Knowing which horses are more at risk and being able to radiograph the feet successfully to look for abnormalities will go a long way towards helping us better care for our Friesian horses with “sidebone.”


Scientific Article: Jones, LE BVSc and Dyson, SJ VetMB, PhD “Radiographic characterization of ossification of the ungular cartilages in horses: 271 cases (2005-2012). JAVMA Vol 247, No. 2, Oct. 1, 2015. pp. 801-811.


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