My miniature Shetland was losing weight (unheard of!!) - he needed daily high calorie food, was laminitic, I could not put him anywhere near frost, and his walking at times was awful. Vet noticed some liver anomalies and with expensive medication he improved a bit and came off meds. I was not convinced though. He is only 9 and yet he was like an old horse and I even wondered about early Cushing's. And then a comment on here prompted me to read up more about salt,
I was intrigued by the potassium levels in poor grass and the ideas that salt makes them drink more, excrete more potassium through the urine....as an ex-nurse this made a lot of sense! So I bough an anodised salt lick at £1.89 and my three ponies fell over themselves to get at it! Within 2 weeks the little one was massively improved. Their salt consumption has now slowed down and they self regulate - if they don't need it they don't touch it. My Shetland is out in the frost, snow etc., fit as a fiddle, feet are great and weight is stable with no extra feed. All for a cheap bit of anodised salt!! (And no, I am not wasting money on 'posh' "8 times the price" Himalayan Rock Salt just because it's fashionable at the moment!)
Part of me is irritated with the vet for not considering this but hey ho all has worked out well and I have a very happy pony!