Here in uk they arent ussually broken to pull a cart until they are at least 2 and a half. A yearling is still growing pyshically and emotionally. In my opinion to break a horse to pull at cart as a yearling, is just asking for future physical and emotional issues. You can do all of the long reining and getting them used to harness and commands tho, while you wait for them to grow older, so none of the time spent is wasted- you get a happier and more well balanced horse at the end of it, in return for all of the time you have invested.
But I notice you didnt comment on future physical issues, because they have started pulling too soon. And I too am talking about lightwieght exercise cart, not heavy wagons. It really seems too young to be pulling anything in my opinion. They are babies at one- not physically or mentally mature.
I know a little bit about driving, so I'm no expert but I believe ground-driving as a yearling is fine. It teachs them the commands and it just establishes the basics. Depending on the horse itself, you could do light work. But remember that it is entirely up to the temperament, build, strength and mental capacity of that horse.
Its always good to have a trainer help you break in for the first time, just so they can give you a hand if they feel you need it.
Getting a feel for the cart I find is fine. Just hooking it up and letting them get used to it. It doesn't mean drive them til they get tired. And if the horse wants to have a little walk, why not? Obviously you're trying to prep them for proper driving, so a little walk wouldn't hurt them.
And I'm sure the OP would have a trainer help her.
Sorry, while im all for getting them used to things, I don't agree with this because the weight of the cart is too much for them, and if you then put in the weight of one human as well, it is considerable for an animal this young to pull, plus they are, at that age, still mentally immature, and by doing this too young you are giving them too much responsibility. So im afraid we will have to agree to differ on this point.
Wow I have never seen so much bad advice on one thread in such a long time.
I am not a driving expert for sure but have helped and watched some of the best in the small equine industry. I have also trained a couple myself
Yearlings are NOT mentally and physically ready to drive. Driving is a dangerous sport and do you really want to put your life in the hooves of a young not yet mentally mature horse??? And what about the horses physcial state?? Yearlings are still growing at a rapid rate and really do not need the pressure of being hooked to a cart.
Just because you CAN do something doesnt mean you SHOULD.
This excuse of doing it young because you can "overpower" them is just insane!
First of all a driving horse should have all the background already done. Such as great ground manners, standing tied, knowing voice commands, knowing whoa means stop this instant etc. That you can do with a yearling.
By the time the horse is 2.5 or 3 they should be very easy to finish training to drive because the groundwork was laid while they were young. So there should not be a need to "overpower" them.
And one thing I know for sure is really you will never "overpower" a horse because ultimately even a miniature is stronger then a human. If you have to resort to "overpowering" them you are definitely doing something wrong
Sophie I hope you will think about this some more and give your horse the time to grow up. Always think long term not short term. Lay a good foundation and you will have no problem when the horse is mature and ready to drive