Chicken in trough

Chickens can't swim apparently. Didn't know that! I was inside and saw the horses run from one side of the paddock to the other and looking back towards the trough. Then I saw a chicken in the truth flapping her wings furiously (and scaring the horses) ...I ran out and rescued her out. She hasn't really been the same since. I'm not sure why. She has one eye closed now too and it seems swollen. Oh dear!