Prospective Evaluation of Techniques for Differentiating Shoulder Pathology As a Source of Forelimb Lameness in Medium and Large Breed Dogs

To assess lameness evaluation, shoulder abduction angles, radiography, and ultrasonography for determining presence, location, and severity of forelimb pathology. Prospective cohort study. Dogs >=20 kg (n=30). Each dog was assigned lameness scores. Shoulder abduction angles were determined. Radiographs of shoulders and elbows were subjectively graded for pathology. One investigator unaware of dog history (lameness, radiographic findings) performed ultrasonographic assessment of shoulders with subjective grading of pathology. Another investigator unaware of dog history (lameness, radiographic, ultrasonographic findings) performed arthroscopic assessment of shoulders with subjective grading of pathology. Elbows were disarticulated and evaluated for gross pathology. Histologic pathology scoring of shoulder tissues was performed. Data were compared for differences among groups, sensitivities, specificities, positive and negative predictive values, and positive and negative likelihood ratios were calculated. Twenty-seven forelimbs were considered clinically normal, 26 had shoulder pathology, 5 had elbow pathology, and 2 had pathology of both the shoulder and elbow. Dogs with shoulder pathology were twice as likely to be lame compared with dogs with elbow pathology. Limbs with medial shoulder instability had significantly higher abduction angles than normal limbs and those with elbow pathology. Radiographs were clinically useful for diagnosing elbow, but not shoulder, pathology. Ultrasonography was clinically useful for diagnosing shoulder pathology other than instability. Abduction angles, ultrasonographic evaluation, and arthroscopic assessments had strong, significant correlations with reference standards. Clinically relevant diagnostic techniques yielded characteristic, repeatable differences in objective and subjective assessments for distinguishing presence, location, and severity of forelimb lameness in dogs. The diagnostic approach to forelimb lameness in dogs should include shoulder pathology as a differential with multiple assessments used to determine the clinical cause of lameness.