Make sure that Snowball CAN sweat. Feel under the "armpits" and see if you feel some dampness. Humor the old lady -- I worry about horses that don't sweat as it can be life threatening, and I've almost lost 2 that way -- when suddenly one year at different times they both stopped their ability to sweat then crashed, and almost "burned". But we were able to save them both that year by stalling them under fans and mist to bring their body temperatures down.
One never did regain her "sweating" and I had to place her up north. The other had a bad summer, and then was fine the next year. Don't know what caused it, or why one resolved, but I'm alway "wary" of horses that don't have some sweat on them somewhere!! LOL