Kerstin Kemlén is a good friend of mine and as a person she is one that goes to the bottom of all issues she is faced with. She is a owner of harness horses with a strong focus on performance. It was a question of performance that led her into the subject bits and bitting and its consequences for horses. In the beginning the question was one of solving a problem for a specific horse in her stable which drove her to explore the topic, but now it has become a question of horse health in general.
Early on Kerstin came in contact with Dr. Robert Cook, who developed a bitless bridle, and they have had an extensive email exchange over the years where Kerstin has raised questions and Dr. Cook answered by the best his of understanding and ability.
The essence of Dr. Cook's research is that bit, regardless of form, material or the quality of the riders hand causes damage to the horse. The damage can range from physical injuries from bit on bars, tongue and teeth into njuries that take a little more time to develop such as breathing disorder and behavioral disorders.
Just as traditional horse shoeing affects the horse negatively the tradition of brideling does the same thing. This colorful image taken from Dr. Cook's website shows by the scale the relative sensitivity to touch the different body parts of the horse have. The red areas represent the areas with the highest amount of sensory nerves. As you can see muzzle and mouth are areas very sensitive to touch.
Being a horse owner is to be aware of what you compromise with and why. I myself have chosen to shoe my horses this fall, and although I know that it costs in the form of hampered hoof mechanism, I´d take it rather than to have a horse rip itself.
I have bitted bridle in the tack room, but I ride using Dr. Cook's bitless bridle. And of course there is a difference in experience! The horse is a good deal stronger in bitless, 16 times stronger compared to a bitted horse according to Kerstin (who happily and readily calculates everything). Such a difference most certainly have an effect on the relative balance of strenght (if I can use that word) between horse and rider.
So when my horse gets Mr Hot in the Hat, that strenght it's really apparent ... but I have not felt unsafe despite some lively gallops. It is possible to make a one-stop rein with the bitless bridle and there is every opportunity to get a low-key communication via the bridle.
The difference is the feeling in the hand, there is no sensory feedback via the reins as one gets when the reins are attached to a bit the horse's mouth. It's actually quiet in the reins ... no chewing, no movement and it's really how it should be according to Dr. Cook. When the horse is working it has its mouth closed and it is still, it is only when the horse eats it should open the mouth and chew.