@KikisGirls actually have no idea, but just recently discovered a hole in the padock near the pond that appears to have been steped right down into, the hole is no wider than her leg and there are quarts stones fist size in it. I think she did it stepping into that hole, or creating it, it may have some ground water errosion in that area. It's fortunate her leg wasnt broken. The stock no longer have access to that paddock.
