Hi Barbara - I can't speak to the question about how young Cushings has been
diagnosed in a horse, but wanted to give you some feedback about my horse's
experience with supplements and 'offness'. He's 20 and started coming out
of his stall stiff, and then would work out of it, this winter. When I
finally decided to have him checked out his x-rays showed serious hock
changes on the stiff leg. Started him on bute and trot work. Within a week
he had his spell of seriously attacking his salt block, drinking buckets of
water and peeing all over his stall! With his fat pockets, long long winter
coat, and age the vet diagnosed Cushings. I had taken him off the bute when
he started peeing so much as I was concerned about a possible connection to
it. Just on the pergolide he started working with no 'offness'!

I'm glad you're having him checked out, too. I have read about the mystery
about how some horses with hock changes are sore and some are not. Makes me
wonder if their body chemistry is the difference. I had switched to a new
multi-vitamin supplement this winter and stopped it when he had his bad
spell with peeing so much. A few weeks after being on the pergolide,
working soundly, and drinking/peeing normally, I gave him some of that
supplement again. He drank down his whole big water tub again that night
and alot of his free choice salt! I believe something in that supplement
threw his system off and exacerbated his Cushings issues and contributed to
his 'offness'. So, have you changed his supplements any prior to this
'offness'? Within the last few months?

Take care, Makyla & 4-legged friends