The UVM Extension Service put together this short (30 second) PSA about sharing the road with horses. I think it actually does a decent job encapsulating good manners.
Have you ever had problems sharing the road with cars?
Tristan is very good now, but he wasn’t always so bombproof. My worst moment was some years ago. I had to ride a short distance on a paved road to get to the state park near my boarding barn. A driver in a sports car revved up his engine, gunned it past us, and passed so nearby I could feel a passing breeze on my skin. If I’d held my hand out he would’ve hit it. It all happened so fast by the time Tristan was reacting the car was well past us; thankfully, he just jumped around a bit on the side of the road and there were no further cars coming.