Something I've done in the past with people like her is to offer to come along to the show and ride the horse for them in one class.
I explain to the client that the first horse show can be dangerous, all of the horses bad quirks come usually out at the first show and they really show what they are made of. So, I'd offer to ride along and, in the event that the horse is calm enough to go into a class with, I'd take the first class on the horse for them. That way, the owner has a 100% unveiled look at the horse and how it measures up to its competitors... if you even make it into the class.
This is a great learning experience for both owner and horse, and it can really open their eyes to how shows are, what judges expect, if the horse is ready, and how the horse measures up.
A very tactful way to offer this is to talk about how the horses first tend to act at one show with all of the commotion, etc. Then, suggest taking the horse to a show without intentions of actually going in a class, just to see how they act. Then, offer to ride for her in a class if the horse is ready, for all of the reasons in the paragraph above. A good owner will listen to their trainer and think it's a great idea.
If she declines, well, the best you can do is offer to come along and help, and let her make her own mistakes.
Owner and head trainer of SE-Wisconsin Horse Care
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