My 17yo pinto mare is utd on all shots etc, always healthy just accident prone. Recently she has begun to doze very heavily. Her head is nearly on the ground and her knees will all but buckle, but she will catch herself then do it all over again. She is perky and will immediatly 'come around' when she see's me coming out ( have checked on her a bunch, this is worrying me) Vet just says she isnt a young filly anymore LOL but I have never seen another horse do this like she does and after loosing my ol man a couple years ago I am more worried than probably should be. Any thoughts? is she just starting to doze harder now?