Magnetic resonance imaging findings in dogs with confirmed shoulder pathology.

Objective: To evaluate the diagnostic potential of magnetic resonance imaging (MRI) compared with a reference standard, arthroscopic and/or open surgery, in dogs with soft tissue shoulder pathology.

Study Design: Retrospective study.

Animals: Dogs (n=21).

Methods: Magnetic resonance (MR) images were retrospectively evaluated in 21 dogs that had surgically identified soft tissue shoulder pathology. The musculotendinous units of the biceps, infraspinatus, teres minor, supraspinatus, subscapularis, and the medial and lateral glenohumeral ligaments (MGHL and LGHL) were graded as either normal or abnormal. Abnormal structures were further classified as being either inflamed, partially torn, or fully torn. Impingement of the biceps tendon was also evaluated. Results were reported in terms of agreement and concordance between MRI findings and surgical findings. Agreement was defined as the percentage of times MRI findings concurred with surgical findings with respect to a structure being either normal or abnormal. Concordance was defined as the percentage of times MRI concurred with the exact surgically assessed pathology when abnormality was identified.

Results: The findings were biceps tendon: 90% agreement with 100% concordance; subscapularis: 95% agreement with 62% concordance; MGHL: 84% agreement with 83% concordance; LGHL: 88% agreement with 100% concordance; infraspinatus: 100% both agreement and concordance; biceps tendon impingement: 90% agreement with 100% concordance.

Conclusions: Soft tissue abnormalities of the canine shoulder were readily identified on preoperative MR images.

Clinical Relevance: MRI shows great potential as a diagnostic tool in the evaluation of canine shoulder disease.