Ultrasound measurement of sole horn thickness in trimmed claws of dairy cows.

OBJECTIVE: To determine whether ultrasound could be used to measure sole horn thickness in dairy cattle after claw trimming with an adaptation of the Dutch method. DESIGN: Case series. ANIMALS: 24 adult Holstein dairy cows. PROCEDURE: Cows were restrained in a standing position, and claws were trimmed with an adaptation of the Dutch trimming method. B-mode ultrasonography was then performed. The transducer was placed on the sole just caudal to the apex of the toe and immediately medial and parallel to the abaxial white zone. The inner margin of the sole was identified as a thin hyperechoic line. Soles were considered to be too thin if sole horn thickness, determined by use of ultrasonography, was < 5 mm. RESULTS: Sole horn, underlying soft tissues, and the distal surface of the third phalanx were imaged in 151 claws. The inner margin of the sole could not be identified in 4 claws, and 37 claws could not be imaged because cows collapsed in the restraining chute. Mean +/- SD sole thickness for all claws was 71 +/- 1.3 mm. Only 1 sole was < 5 mm thick. The lateral front claws were significantly thicker than the medial hind claws. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that ultrasound imaging can be used to determine sole thickness in dairy cattle after routine claw trimming.