We used the garden hose sprayer to wash our horses 20 years ago. They had never had a bath and were really ugly about it at first. Being able to stand back and squirt away and let them fuss all they wanted to was wonderful! After just a couple of "baths," the horses learned to stand still and let us get it over with.
I will use the same technique with the new horses - not that we bath them over much when it's so dang cold outside!