Bathing and picking up and cleaning your horse's hoof is part of a desensitizing program when a horse is not comfortable with these procedures. People gladly spend the time desensitizing their horses up to this point and then they stop. Naturally each horse will respond differently to each sense. Some will need desensitizing to only one where another may need to be desensitized to all of the senses. When working with horses we must always remember they are animals who originated from the wild.
Horses still possess the natural defense instincts of their ancestors.
These natural instincts are what protected horses throughout the years while being prayed upon in the wild. Basically when horses reacted naturally, which was frightened of the unfamiliar noises, sounds, or sights, they ultimately survived. When a predator did engage them, their most violent of the senses, which is touch, reacted. Touch will quickly activate the kicking, striking, or biting instincts until they are taught differently. Touch is the only sense that will cause a horse to react with fighting instincts instead of flight.