Quantitative evaluation of the relationship between dorsal wall length, sole thickness, and rotation of the distal phalanx in the bovine claw using computed tomography

Abstract

Computed tomography (CT) was performed on 800 untrimmed claws (400 inner claws and 400 outer claws) of 200 pairs of bovine hindlimbs to investigate the relationships between dorsal wall length and sole thickness, and between dorsal wall length and the relative rotation angle of distal phalanx-to-sole surface (S-D angle). Sole thickness was 3.8 and 4.0mm at the apex of the inner claws and outer claws, respectively, with dorsal wall lengths <70mm. These sole thickness values were less than the critical limit of 5mm, which is associated with a softer surface following thinning of the soles. A sole thickness of 5mm at the apex was estimated to correlate with dorsal wall lengths of 72.1 and 72.7mm for the inner and outer claws, respectively. Sole thickness was 6.1 and 6.4mm at the apex of the inner and outer claws, respectively, with dorsal wall lengths of 75mm. These sole thickness values were less than the recommended sole thickness of 7mm based on the protective function of the soles. A sole thickness >7mm at the apex was estimated to correlate with a dorsal wall length of 79.8 and 78.4mm for the inner and outer claws, respectively. The S-D angles were recorded as anteversions of 2.9° and 4.7° for the inner and outer claws, respectively, with a dorsal wall length of 75mm. These values indicate that the distal phalanx is likely to have rotated naturally forward toward the sole surface. The distal phalanx rotated backward to the sole surface at 3.2° and 7.6° for inner claws with dorsal wall lengths of 90–99 and ≥100mm, respectively; and at 3.5° for outer claws with a dorsal wall length ≥100mm. Dorsal wall lengths of 85.7 and 97.2mm were estimated to correlate with a parallel positional relationship of the distal phalanx to the sole surface in the inner and outer claws, respectively.