You didn’t mention what breed of horse you purchased. But I, too, suggest having her teeth looked at again, fecal check for worms. I used a feed made by ADM called MoorGlow – it did absolute wonders for our 28 year old standardbred. Put weight back on his top line and over his hip/ rump area. The feed is pricey, but it really works! We also fed him Senior Glo with the MoorGlow and Timothy alfalfa cubes mixed with warm water. He gained back his weight and maintained it till he passed away at 32. Good luck !!!!!