Best of luck to you and your horse, but I have to say keeping the product constant in their system I think helps in the long run. My horse is 30 and we ride almost every day which in the South Florida heat really sucks.  He has gotten much better over the years and acupuncture has helped the most.  He used to be bone dry, but now we can ride and he is much better.  I actually bought him a swamp cooler which runs outside his stall and blows the cold air all the way to the back of his stall so he has air conditioning once it gets really hot here.  Running a fan circulating the hot air really did not do anything to hep him.  He loves his swamp cooler,

I did talk to the man who developed One AC and was told for my horse I should keep him on it year round, which I did for a couple years but since them I have gone another route which really seems to be working for Spirit.