Has this horse ever been trail ridden alone? If not, then that's where I
would start. So many horses just learn to be dependent on a buddy on the
trail. If he's taken out alone then there is no lead or follow - just go.
This is my first recommendation. Do this till the horse is very comfortable
alone on the trail. Then introduce riding with a buddy again.
How much schooling does the horse have? If he is knowledgeable about the
aides then I would make it more uncomfortable for him to stop while in the
lead than to go forward. Use turn on the forehand/haunches, leg yield
exercises, side pass, small circles to work on bending, etc...These are not
_punishment_ per se, rather you are giving the horse a choice - either go
forward nicely in the lead at an <easy> walk or trot or whatever or have to
*work*. I would start these exercises in a pasture first - preferably
something that is close enough that you can give immediate reward.
So....you two are out in a pasture working on this, the horse stops, your
friend uses some of these exercises, her horse goes in the lead for a short
time, that's the end of the lesson. Get off and walk in to the barn.
For the first few times, the _first_time you get some forward motion while
the horse is in the lead, quit and go home. Remember, ask for a little,
reward and then the next time ask for that amount again, then a little
more. Gradually increase either the amount of time the horse is in front or
the number of times the horse is asked to lead. This is *not* a quick fix
:->> If your friend is not prepared to take the time on any given day
(because maybe you would both like to get in some actual conditioning <g>),
then don't work on it that day. In other words, don't start something your
friend isn't prepared to work on till she gets that desired response and go
out knowing that you may not get in any conditioning while working on this
on a particular day.
I hope this helps. I have not had too much experience with this particular
problem - I ride alone 95% of the time so riding with a buddy is a real
treat for me and my horse!
Tina and the crew
hickst@nichols.com
Huntsville, AL