I have pet insurance for my dog which has been a completely and total godsend and I would recommend it whole heartedly to anyone and everyone who could possibly listen! Petplan is the company for small animals that I endorse beyond any doubt.
Naturally, having such great experience, I wanted to get insurance for my horse but I was frustrated to find that almost all equine insurance revolved around mortality insurance. Even more distressing was that most companies would only insure your horse for how much he was "worth" which doesn't do a whole lot of good for those of us who just want to help our best friends if they need surgery!
I'd basically given up on the whole idea when my trainer turned me on to Great American Insurance (through Wells Fargo). They were the only company we could find that would insure your horse for major medical regardless of how much it was "worth."
I got my horse for free but I was still able to insure him up to $10k or $15k for major medical / surgery. You do have to buy mortality insurance along with major medical but it's worth it for the peace of mind.
Horse insurance to me isn't about compensation if he dies (which is good because his mortality payout is as low as it gets) but it's about enabling me to do absolutely anything and everything to save his life if he ever needs it.
Their website is Great American Insurance Group, a Specialty Insurance Provider -
but I just purchased it through a Wells Fargo agent so that may be the way to go.
I haven't had to use it yet but it's not too terribly expensive and worth it for the peace of mind IMO. My trainer had to use hers several times and actually was able to use it to get stem cell therapy for one of her TBs.