Hello, I have my first pair of Ducks and my 5 week old Rouen Drake gets an enlarged neck/breast on the/his right side. I think I understand they hold food in their esophagus but would expect it to be symmetrical. Sometimes it goes down to match the left side and his upper breast/esophagus looks the same side to side. My hen always looks symetrical. Read up on ailments and no nasal discharge and when I massage the area do not feel anything hard or any obstructions. Is this normal or might a condition be developing? Thank you!