I always start my horses out very slowly on the lush Spring grass, but have never had a horse that has had any problems. When I got Annie it was at the end of summer and everything was dry here, but I was told that she had foundered slightly in the past, and had also just recovered from an abscess when she came to me. The farrier couldn't see any indication of prior problems when he did her first trim here and I told him I would start her slowly as well. I never let them out if we have frost, but He also suggested that I not let her out to graze when the low and high temps were really varied causing increase sugar. I tried to research prior threads to see what that temp spread would be because the spread here has been 30 degrees between the low and the high each day even though it's not freezing. I found a thread where Chandab had provided a link to wwwsafergrass.org but their website now just directs you to a facebook page. I just want to be extra careful with her, because she is turning out to be a very good driving horse and It would crush me to have problems with her feet.