Texas Equine Veterinary Association

www.teva-online.org • Page 6 Lameness originating from the scapulohumeral (shoulder) joint is relatively uncommon. Due to the relative infrequent occurrence of lameness originating from the shoulder, treatment is often delayed. DIAgnosIs of shouLDeR LAmeness Both a standing musculoskeletal exam and traditional lameness exam are important when attempting to localize lameness in the shoulder. Localization can be straightforward when there is associated swelling/heat or pain on palpation; however, in more subtle cases of suspected upper limb lameness, intra-articular anesthesia of the shoulder is necessary to confirm clinical suspicion. Acute lameness is typically associated with shoulder fractures/ luxations along with varying degrees of swelling in the affected area. In contrast, joint effusion cannot be palpated in subtle lameness originating from the shoulder joint because of the extensive musculature overlying the joint. While effusion is not always evident, sensitivity to deep palpation near the greater tubercle of the shoulder can sometimes elicit a positive pain response. Similarly, in cases of bicipital bursitis/tendonitis, pain is often elicited when lateral pressure is applied over the biceps tendon. Less specific signs of shoulder lameness include muscle atrophy, pain on extension and/or flexion, and a decreased anterior phase of the stride during the moving musculoskeletal exam. If lameness is suspected to originate from the shoulder and musculoskeletal examination does not definitively localize the lameness to the lower limb, intrasynovial anesthesia (IA) of the shoulder or bicipital bursa should be performed using the following recommendations. shoulder Intra-articular Anesthesia — an 18-gauge 3.5 inch spinal needle should be inserted into the notch between the cranial and caudal aspects of the greater tubercle. The needle should be directed parallel to the ground and toward the contralateral elbow until bone or cartilage is contacted. Confirmation of proper placement is noted if synovial fluid is obtained. Approximately 15-20 mls of mepivicaine should be deposited into the joint. Care should be taken to avoid depositing block outside the joint because the suprascapular nerve can be inadvertently blocked resulting in lateral subluxation (sweeny) of the joint at a walk. If the suprascapular nerve is blocked the horse should remain stalled until the block has worn off. 1 Bicipital Bursa Intrathecal Anesthesia — an 18-gauge, 3.5 inch spinal needle should be inserted approximately three inches distal and two inches caudal to the most prominent aspect of the cranial portion of the greater tubercle of the humerus. The needle should be directed medial and proximal until it contacts bone. Approximately 20 mls of mepivicaine should be deposited into the bursa. 1 Following localization of lameness to the shoulder region, medial-to-lateral radiographs should be performed while standing with the affected limb extended cranially. Ideally, the scapulohumeral joint should overlay the trachea when obtaining shoulder radiographs (Figure 1). A skyline radiographic projection of the shoulder should be performed to delineate greater tubercle/ intertubercular groove of the humerus lesions, as greater tubercle lesions can often appear normal on standard medial-to-lateral projections (Figure 2). 2 It is not uncommon for shoulder survey radiographs to appear normal. In cases where shoulder radiographs appear normal despite localizing the lameness with diagnostic anesthesia, one should be highly suspicious of osteochondrosis lesions (OC). 3 Confirmation of OC lesions of the shoulder can be difficult; contrast radiography can sometimes be used to confirm the presence of a cartilage lesion that is not apparent on normal radiographs. Lameness localized to the bicipital bursa warrants radiographic and ultrasonographic examinations. Nuclear scintigraphy (bone scan) is a viable diagnostic modality when survey radiography and/or ultrasonography has been unrewarding. SHOulDER lAMENESS in horses chad marsh, dVm, ms, dacVs Texas A&M Univeristy Veterinary Medical Teaching Hospital

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