Lame left rear leg

My BABY, 7 year old Kentucky Mountain horse came up lame last night and would not put any weight on his left rear leg. We had to push him into the barn and his stall. He was shaking in his rear end, like he was cold. Called my Vet and he told me it could be an abscess. Any ideas?

Move this to the Horse Care section - this is the Rider’s Care section…

The only things that make them three legged lame are abscesses and fractures. Nope it is the former. Agree this is better served for the horse care forum.