I keep a couple different things on hand. I feed a tablespoon of regular sea salt in AM and PM grain meals daily. If we’re going to have a prolonged heat wave, I might add Apple-A-Day as well. If I know we’re going to be showing or hunter pacing in hot weather, I might give salt + a tube of ElectroPlex the day before and the day of. It really depends on the horse and the situation.
My senior gelding went through a rough couple of weeks a few summers ago when he seemed really lethargic, wasn’t eating or drinking well, just seemed off. We were all ready to test for Lyme when my old school vet said to try giving him a tube of ElectroPlex every day for 7 days. Within 48 hours he perked back up and was well on the way back to his usual self. It’s good stuff.