mbender, prone does mean that she has had it before and is more likely to get it again. Obviously any horse can get lamititis, its just a term which is used.
loosie, the mare is kept in a little paddock with little feed, the hoof feed which she uses is called Happy Hoof and is a chaff substance. I think she has that and I suppose some oats or pony nuts. She is over weight, and by a pain to ride I mean is very strong and nappy and generally hard to ride. The mare gets lunged a couple of times a week but not very often.
luvs2ride1979, Thank you! I will have a look at those products and suggest them to her!