Don't run the hose full pressure, just dribble to start. Hold it to your side as you face her hindquarters, Move it half way toward her then back, holding it low. Slowly swing it back and forth then gradually work it closer until it hits her hoof then away. Don't go any higher than her knee and keep up the rhythm. When you feel she will be okay with it go to her hoof then up the outside of her leg to her rib cage, not the shoulder. If she moves she's concerned about getting water in her ears so just go back to the first exercise. You can also offer her a small treat whenever she stands quietly. If you go this route, have lots. To prevent her trying to mug you or your pocket always offer the treat with an outstretched arm so she has to turn her head away from you, even a little.My first treat would be her standing when the water touched her hoof. Again and again, then her knee, again and again, etc.