I've been adding a whole bunch of other things into their food and I keep thinking ... why not salt? I eat so much salt in my daily diet and I deprive them of it!
I've found out about the best salt there is for rehydration and health is the Himalayan one. Check it out here. Apparently it has all 84 minerals that are needed for health. I'm going out shopping for it today! Super solution to a problem that has bothered me for a long time - I've always felt it was unfair to keep salt out of their diet.