I am starting my senior mare on Senior Flex with comes from SmartPak. As I was looking through the choices I noticed you can add an electrolyte supplement pretty cheaply. We're in Texas, and it gets darn hot in the summer. My mare will be in light work, walking about 45 minutes 3x per week. Does anyone have an opinion on whether an electrolyte supplement would be warranted to be on the safe side? She'll have free access to her stall but her paddock is not shaded.