I'm looking into buying a cooler for my horse, instead of using my trainer's. However, under one description of a cotton sheet (100%), it said shrinkage would be 15%. I am looking at a 100% cotton cooler that doesn't have a shrinkage warning. However after calling State Line and asking, the lady who didn't know a thing said it'd shrink. My horse takes a 75". Should I get him an 80" since the one I use at the barn is 80"?