For you all who are putting the cooler on under the sheet/blanket, is that just to keep the cooler clean or inplace? When layering, I always put the cooler on over, and it whicks the moisture through the underlayer to the outside of the cooler. Then I remove the cooler and leave them with their underthings on. I would think putting something over the cooler would trap the moisture?
What I do when my horse is wet is just put one of those fitted fleece coolers on, and take it off later when he’s dry.