The stop or Whoa is one of the most important things a driving horse will learn. If you don’t have a good whoa and stand still to begin with it will not develop once they are hitched to a vehicle. This must be taught without the cart. I often use a bit of positive reinforcement to teach this, clicking when they stand still and giving them a treat, usually a few hay pellets. This type of reinforcement can result in a horse or pony who slides to stop when asked to whoa!
Something I realized a few years ago with Zorro is that he did not connect the pressure of the bit with his feet. Instead he thought the bit was about his mouth. He had a wonderful whoa and a great stand still but those where things he connected with my voice commands. So it was time to pair that voice command with my hands and the lines.
He was wanting to lean on the driving lines when I would pick them up and ask for some connection. He would get heavy on his front end and then gape his mouth and using his tongue he would push the bit to the back of his mouth and CHOMP CHOMP CHOMP.
I went back to the basics, ground driving and long lining, and asked for lots of stop and back up! Of course I would use my voice command for the whoa, pairing that with some connection with my lines. I would pick up the lines FIRST, put some connection into the lines and if he didn’t do anything I would wait a few seconds then say Whoa. Then he would get a treat. I always started with my hands being very soft because the softer you start, the softer you can stay. The reason it was so important for Zorro to pair the connection with the lines with his feet is so I can effect a change in his feet at all gaits when we are driving.
If your horse is chomping the bit, gaping it’s mouth or going behind the vertical when you lift your lines it may be because it isn’t connecting the pressure on the bit with their feet. Just a little something to consider!