I think that is a great thing for you to do. I have rescued 2 horses before. The first one was so skinny she looked like bones with skin just wrapped around them and yes it did lead to some big vet bills she had some teeth prolbems from being so malnutrioned but she had a happy ending we sold her to a great family that actually got a hold of us last spring after about 5 yrs and said they had found our number again and wanted us to know she was doing great the other one I got was just last winter, looked about the same as she did but luckly didn't get us into no big vet bills and she has found a new home with one of my cousins and yes i'll propable find another one day to take in and I think if you are willing to spend some time and money it is a great idea!
My spanish mustang was a rescue. There is nothing in the world like a rescue horse. Once you put some weight on them, earn their trust and really understand each other you will never find a more greatful animal.