Ultrasonographic anatomy of the dorsal region of the carpus of the dog.

The dorsal region of the canine carpus is anatomically complex and its normal ultrasonographic characteristics have not been published. The aims of this prospective, descriptive, anatomic study were (a) to describe the normal ultrasonographic appearance of the dorsal carpal structures in medium to large breed dogs, and (b) to describe a standardized protocol for evaluations. The final study, based on the methodology developed in a pilot study performed in twenty-two carpi, comprised two phases: (a) identification phase, in which a correlation between ultrasound and dissection and anatomic slices was performed in forty-eight cadaver carpi and the ultrasonographic protocol was developed; and (b) descriptive phase, in which the ultrasonographic characteristics of the examined structures in 23 carpi of 12 alive adult and healthy dogs were recorded. The tendons of the abductor pollicis longus and the extensor muscles of the carpus and digits, the dorsal ligaments of the carpus - including the medial and lateral collateral ligaments - the extensor retinaculum, a distal radioulnar fibrocartilage and the regional osseous surfaces were ultrasonographically identified and described. Findings from the current study can be used as a reference for ultrasonographic examinations in dogs with injuries or other diseases affecting the dorsal region of the carpus.