This dog came to me on emergency for suddenly not wanting to bear any weight on a front limb. The owner was un-aware if she had been hit by a car, shot, or some other injury that may have happened. Upon arrival she would not place her left front limb on the ground at any time. It also appeared to point more lateral (outward) from the elbow down. There was no pain response of flexion or extension of the shoulder. Prior to any flexion/extension of the elbow. There was abnormal bony protuberances on the medial (inside) of the elbow joint.
Below is the first radiograph that was taken with the dog laying on her side (lateral view) with the injured leg down with the other leg moved out of view. I was looking for fractures, luxation/subluxations, and other bony injuries. Upon inspection, the elbow joint (red arrow) space appears slightly enlarged but not other abnormalities were seen on this view.
I highly recommended taking another radiograph with a different view to see bones and joints at a different angle. The owner was cautious, but decided to do so. the radiograph below called an AP (anterior to posterior) or DP (dorsal-palmar) that shoots from front to back of the limb.
Purple arrow: Shoulder joint (humerus and scapula); Blue arrow: Ulna/radius; Green arrow: Humerus
This radiograph shows that the elbow joint is luxated (dislocated). The humerus is moved toward the body and the radius/ulna are moved away from the body. It is likely because of the severity of the luxation, that the stabilizers (tendons/ligaments) are torn. This dog was sedated heavily and the elbow was replaced, but in this case the joint would re-luxate as soon and the leg was extended. Normally, luxations are treated via spica splint (straight leg with splint for stability), surgery, or amputation. If the luxation is severe, like this case, it is likely that even with splinting, that the elbow will likely re-luxate once removed. In that case, surgery or leg amputation are the best options for treatment.
NOTE: This case shows the IMPORTANCE of taking several different radiographic views for appropriate diagnosis and correction. You may not see a problem in one view but another may give you an answer!!