I have a similar problem with my "ancient" mare...it could be Cushings, but after even reading the books and other vague information, I'm still not entirely certain what that entails. Having a Cushoid, will you enlighten us?
My old mare will shed in spots, but some/most of the hair will hang tough until it's dang near time to start growing it again for the coming winter (Wisconsin winters...never a nice thing!)
My other 15-year old mare is just the opposite...always looks fat & sassy, and never gets grain of any sort since all she has to do is LOOK at it to put on weight. The old one gets Senior feed + Weight Builder, and all the hay she can eat, but it's not helping.
Picture a very hung-over Phyllis Diller and the very fat Kirstie Alley in the same pasture....well, you get the idea!!
Thanks for listening, and all comments welcome!