Computed tomographic measurements in 110 front hooves of non-lame Thoroughbred racehorses and Warmblood showjumpers.

Abstract

Background: There are no published reference ranges on computed tomographic (CT) hoof wall and sole measurements.

Objectives: To establish reference ranges for CT measurements of the hoof wall and sole in non-lame horses, and to investigate associations between measurements and signalment, laterality, and medial or lateral sides.

Study design: Retrospective, cross-sectional study.

Methods: Soft tissue reconstructions of fan-beam CT studies of 110 front feet of 56 non-lame horses (30 Thoroughbred racehorses, 26 Warmblood showjumpers), performed in non- to semi-weightbearing positions, were analysed. Hoof wall thickness and its layers were measured at standardised sites. The dorsal hoof wall to palmar length of the distal phalanx (DHWDP) ratio was calculated. Paired sample t-tests assessed differences in medial and lateral measurements. Multivariable mixed-effects linear regression models evaluated associations between the measurements and explanatory variables.

Results: Reference ranges were established; the mean total dorsal hoof wall thickness was 14.03 ± 1.37 mm in Thoroughbred racehorses and 15.79 ± 1.41 mm in Warmblood showjumpers. The mean DHWDP ratio was 0.24 ± 0.02 in both breeds. The sole was significantly thicker laterally than medially at the palmar measurement site, perpendicular to the ground (mean difference: 2.12 mm, 95% confidence interval [CI] 1.57, 2.67) and to the surface of the sole (mean difference: 2.08 mm, 95% CI 1.50, 2.66) (p < 0.05). Only bodyweight:height ratio was significantly associated with proximal, middle, and distal dorsal hoof wall thickness across all layers (p < 0.05), except the middle dorsal combined corium and stratum internum measurement. Differences persisted between medial and lateral sides even after adjustment for signalment and laterality (p < 0.05), apart from the sole measurements at the middle measurement site.

Main limitations: Results may not be applicable to other breeds.

Conclusions: The established reference range of hoof wall and solar CT measurements in non-lame horses can aid accurate interpretation of CT studies of horses with foot pain.