I was gone on a week long vacation with the family, and we had a friend feeding and watering our animals. I came home and noticed my coffee can of cooking oil had disappeared. (it had been used to coat their legs when I was dealing with leg mites) I went to go wash out the waterers in both of my pens and they had cooking oil in them! She somehow thought the cooking oil was water I had sitting in there and added it to my waterers. I have no idea how long she had been using it or how much was in each one. They were really greasy though. I washed them out and put in fresh water. My chickens are all acting normal, but could this have harmed them?