Gone

Fantastic dogs. Pushing this to the top after church to see if any takers. Good luck!

I know a rancher with a dog of this exact cross and it's a great dog. I would love to give these guys a home but I live on only 8 acres and would have to keep them in a small fenced yard to keep them out of trouble which I would hate to do.

They have such a strong herding, protective instinct from centuries of breeding, if they would ever identify your colts as their herd they would guard them with their lives. I wouldn't know how that could be accomplished, but maybe a professional trainer would?

My uncle in Comal County had a Great Pyrenees that kept jacking with his miniature donkeys. He, per the recommendation of a trainer, bought a training collar brand called DOGTRA. It had a setting to vibrate, nip or shock.
He never shocked him and only vibrated him a couple of days training and he never bothered the little donkeys again but still protected them and his goats.
Maybe OP try talking to a trainer or try the above. That way you could get to keep and use your dogs?

Extension office/A&M have a livestock dog program. Make a dangle stick.

Dangle stick/chain drags