And they can founder if they are sick with fever... something to be aware of.
I know ponies are susceptible, and Bay is a little cresty, so I think bringing them in at night and feeding them hay in the stall before turnout is good. Let them fill up on bland stuff so they are at least full and grazing slower when they do go out.
We have been feeling both of their feet for hotness. I didn't know about the pulse though.