How do you get your horse to drink out on the trail, from a stream or lake?  My horse will barely cross water, let alone drink from moving water, at least he hasn't yet.  I am guessing this is one of those things where you simply have to be out long enough for the horse to get thirsty enough to drink. but I wonder how dehydrated he would get before drinking. 

Also, what's the key to getting a horse to stop and pee on a long ride?  My horse will hurry back to his favorite spot in the paddock after a long ride, just to pee, like a little kid running for the bathroom.  He will hold it the whole trailer ride home too :(  Actually I think he pee'd once in the trailer, but only after the horse next to him did - hahaha.

*

Learn to  tell if you horse is getting dehydrated. Pinch a tent on his shoulder, press on his gum, listen to his gut sounds. These signes will help you know if he is getting dehydrated.

Endurance and CTR riders are always worrying about hydration on long rides. It took my horse a few rides to learn to drink from mud holes. First time or two he would turn up his nose and say thats not my water. It helps if the other horses you are riding with all dunk their heads and slurp up water. They soon learn not to pass up water.

Give him time to drink. If he is thinking about it and see other horses leaving, he will loose his desire to drink.

Wade out and let him splash and play in the water.

I use electrolytes a lot in the summer. If you do use them, make sure the horse has plenty of opportunities to drink. It's like you eating a salty piece of ham, you know how thirsty you are all afternoon after eating it. It's not right to give the horse electrolytes as you leave the trailer and then not see any water for two hours.

The old saying is you can lead a horse to water but you can't make him drink. So trick him!  Mine will gobble down soaked beet plup.  So I soak up some beet plup and make a real soupy mash. I usually add my electrolytes to the mash, and give it to the horse AFTER he has had an opportunity to drink. Once he has drunk all he will drink. He gets more fluids with the soaked plup.

Ask the same question on www.endurance.net or www.natrc.org Both those are long distance riding groups.