I have a 23 yr old blackneck swan. My prior experience has been that aged swans (mutes & blacknecks) develop weakness in left leg. In past I have treated with prednisone. This blackneck has been having problems with left leg but he has developed what appear to be blisters -inflated fluid pockets in the webbing of the bottom of left foot. I realize the leg weakness is probably arthritis but I have never dealt with the blisters. Any info or treatment suggestions will be appreciated. Thanks.