This appears to be a possible slipped tendon, etc., We are sending an email to our veterinarians to see if this is the case. If it is, not much can be done. Most slipped tendons which can often occur in waterfowl have poor prognosis for surgery.

You should take the swan to an avian veterinarian specializing in waterfowl to see if there is way to help rehabilitate the injury without surgery, i.e., splints, etc. But, you should do this immediately as further injury may occur and more importantly to ensure that the swan is not in pain . Good luck. The Regal Swan