Orthopedic and ultrasonographic examination findings in 128 shoulders of 64 ultra‐endurance Alaskan sled dogs

Objective To determine the location and periarticular shoulder‐muscle‐abnormalities detected via orthopedic examinations and ultrasonography in ultra‐endurance Alaskan sled‐dogs, returned from an ultra‐endurance sled‐dog‐race prior to finishing it. Study Design Prospective clinical study. Sample Population Sixty‐four dogs (128 shoulders). Methods Dogs were classified based on clinical evidence of shoulder pain (SP versus control). Orthopedic examination findings, shoulder‐abduction‐angles (SAA; before‐ and during‐anesthesia), and ultrasonographic findings were recorded. Relationships between orthopedic and ultrasonographic abnormalities were compared. Results Pain was elicited on 55/128 shoulders; 73 shoulders were pain‐free. The most common painful structures included the biceps‐tendon (BT; 30%), triceps‐muscle (28%), and infraspinatus‐muscle (25%). SAA ranged between 25° and 75° among groups, including pain‐free shoulders in dogs without lameness. SAA was greater when dogs were anesthetized (46.3° ± 14.0° vs. 47.8° ± 12.0°; p = .03), especially in SP (mean increase of 3.49° ± 8.85°) compared to control (0.03° ± 7.71°, p = .009). Overall, 103 ultrasonographic abnormalities were detected (SP: 44; control: 59). The most common ultrasonographic abnormality was fluid surrounding the biceps tendon, similarly distributed between groups (SP: 39/44; control: 57/59). Most chronic ultrasonographic abnormalities affected the BT (15/103 abnormalities). No associations were detected between ultrasonographic abnormalities and clinical findings. Conclusion Shoulder abduction varied greatly and reached up to 75° in normal joints. Ultrasonographic shoulder‐muscle abnormalities were common but did not seem associated with clinical findings. Clinical significance Interpretation of shoulder abduction warrants caution, and the presence of fluid around the BT may reflect a physiologic adaptation to racing, rather than a pathologic change in ultra‐endurance Alaskan sled‐dogs.