Yeah ok I went through and re-read the whole thing! I guess I am getting threads confused now! Ahh that's bad! Lol definitely get that pool fenced in! Or let the BO and handlers know you DON'T want your horses there to graze. Or you'll take your business and money somewhere else. That's not worth havign to pay so much in vet bills.
Sorry that your horse was hurt. But the BO's responsibility is to care for your horse. They are paid to do so, and no fence around a pool is asking for trouble. What if it was a young child. AS far as your horse Yes it does look to be on the thin side. Sunken withers, no top line over the croup area. Looks like it could use a few wormings and some extra feed. Hate to say it but your barn owner isn't doing nothing but abusing your horse. If the BO doesn't see this I would find a place to go quickly
Its not her horse. BUT next time it could be. Please think about your horse! Do you want her to get hurt like that? I have had friends that thought it would be nice to let the horse graze around the pool untill a few hours later they found him floughting dead in the pool. Horses don't think "OH CRAP I fell in the pool." They think "OMG WHAT HAPPEND!"