Ultrasonographic Imaging and Thickness Measurement of the Sole Horn and the Underlying Soft Tissue Layer in Bovine Claws

Ultrasonographic imaging and thickness measurements of sole horn and underlying soft tissue layer were evaluated in 100 bovine claw specimens. The claws were trimmed and examined in longitudinal planes using a 7.5 MHz linear transducer. The sole horn, underlying soft tissue layer and distal surface of the distal phalanx of all claws were clearly visualized. The sole horn had a heterogeneous hypoechoic appearance; the underlying soft tissue layer was predominantly anechoic. Corium and subcutis could be differentiated. The best imaging of these structures was achieved in claws with less than 10 mm sole horn thickness and soft sole horn. Imaging of the dorsal wall structures was more difficult. In each claw, B- and A-mode measurements of horn thickness of sole and dorsal wall and distance from outer claw surface to distal phalanx surface were made at three marked points on the weightbearing surface and at one point on the dorsal wall. In 10 claws, CT-images were taken and the horn density was determined. All claws were then frozen, transected and anatomical reference measurements were made after thawing. Statistical correlation coefficients of 0.88 and higher were found for B-mode ultrasonographic and anatomical measurements of sole horn thickness. A-mode proved not to be useful for the sole horn thickness measurement. B-mode ultrasonography was carried out successfully in the claws of five living cattle.