Thank you for that. A friend told me years ago that horses don't receive patting as well as rubbing/scratching. I found that to be generally true, in small ways. It's good to take these things into consideration, particularly when stroking/wither scratching might simply be a more naturally effective praise. Patting (with or without visual confirmation of the source) is not relaxing; even humans typically only do this to each other or accept it of each other in states where excitement is appropriate. Massage therapists do not remove their hands haphazardly or frequently from a client for the very reason that there is a physical and mental reaction to being touched, and then experiencing the absence of that touch. Patting isn't inhumane by any means, but if we're going by what a horse naturally sees as a positive 'feel good', then why would we choose the pat over the wither scratch? Just seems less practical, really. That said, I believe that scratching is just the icing on the cake after "release" (the allowance of relaxation). I would be interested in what happens when patting is used in conjunction with allowing the horse to 'relax'. Does patting then become a cue for the horse to relax? Does the horse then associate patting differently? Would patting then lower the heart rate instead of increase it? I wouldn't be surprised at any of those things.
No diet, no hoof. No hoof, no horse. No horse is not an option!