By a cat!!! I put our cat Bailey up on one of the fillies I look after and he layed down on her back like he meant to stay forever! He kind of hugged her withers to keep his balance. The filly, Senza, seemed to enjoy it and even took him for a little ride on her back. It was sooo cute!
She doesn't fear anything and I guess cats don't faze her either. Bailey enjoyed it a lot until one of the other foals came up and tried to knock him off when he was sniffing him!
My Uncle took my camera on a trip but when he gets back I'll try to take some pics and put them up.