I just started to notice that my male Peking duck will not put pressure on his feet. For example, I will lift him to help him out of his pool, but when I go to set him down on the ground he will not put his feet down to land. Another example is that he will not run. He will walk, and is walking normally, but when herded back into his pen he will not go and faster than what looks like a painful "jog". He waits to be picked up and carried which is unlike him normally. He normally does not like to be held. Does anyone have any suggestions as to what could be going on?