Toby is obviously telling you that 3 one hour walks a day in this heat is too much. You give him plenty of exercise, he will be fine if you cut some of it out until it cools down. I don't know if you mean a walk for exercise or you let him outside for an hour on leash. I can't take Chloe out for more than about 30 min, but we power walk very fast for exercise. I don't know how you even get him to walk that much! I don't mean this in a mean way because I know you're a great chi mom, but I think getting Toby out for 3 hours a day in 100 degree weather is a little cruel. I know you are only trying to do what's best for him, but I think you should listen to his body language. It is too much for him. It's great that you spend so much time with him, and I think that it would be fine to go back to that much exercise once it's cooled down.