CT Evaluation of the Sagittal Ridge of the Cannon Bone in Young Race Horses

Computed Tomographic Evaluation of the Sagittal Ridge of the Third Metacarpal Bone in Young Thoroughbred Racehorses: A Longitudinal Study

Animals (Basel). 2024 Mar 6;14(5):812. doi: 10.3390/ani14050812.
Authors
Koppány Boros 1 , Sue Dyson 2 , Ágnes Kovács 3 , Zsolt Lang 3 , Annamaria Nagy 1
Affiliations

1 Department and Clinic of Equine Medicine, University of Veterinary Medicine Budapest, Dóra Major, 2225 Üllő, Hungary.
2 The Cottage, Church Road, Market Weston, Diss IP22 2NX, UK.
3 Department of Biostatistics, University of Veterinary Medicine Budapest, 1078 Budapest, Hungary.

PMID: 38473196
DOI: 10.3390/ani14050812

Abstract

Metacarpophalangeal joint region pain is a common cause of lameness in racehorses. Radiological abnormalities in the sagittal ridge (SR) of the third metacarpal bone have been associated with joint effusion, lameness and reduced sales prices. The aims were to describe computed tomographic (CT) appearance of the SR in racehorses, and to document the progression of these findings over three assessments. Forty yearlings were enrolled at the first examination (time 0). Re-examinations were performed twice, approximately six months apart on 31 (time 1) and 23 (time 2) horses, respectively. Computed tomographic examinations of both metacarpophalangeal regions were performed with the horses in a standing position. Computed tomographic reconstructions were analysed subjectively and objectively. The mean Hounsfield Unit values (Hus) of eight radial segments and location, size and shape of hypoattenuating lesions were recorded. Mean Hus at time 1 were higher than at time 0. There was no difference between mean HU at times 1 and 2. The mean HU values of the dorsal half were higher in the right forelimbs and in fillies. Hypoattenuation was identified in 33/80 (41.3%) limbs at time 0, in 22/62 (35.5%) limbs at time 1 and in 14/46 (30.4%) limbs at time 2. All hypoattenuations were located in the dorsodistal aspect of the SR. The most common shapes were hypoattenuating lesions elongated proximodistally and those extending towards trabecular bone. An increase in attenuation of the SR occurred in the first six months of training. Hypoattenuating lesions could decrease in size and could resolve during early training. In this population, these lesions were not associated with lameness.

Keywords: adaptive remodelling; computed tomography; fetlock; osteochondrosis; racehorse; sagittal ridge; third metacarpal bone.