Hello. I recently bought and viewed the leerburgs raising a working puppy. I'm nearly sure in the building engagement section they done work with a harness. A helper would hold the pup on a harness and Michael Ellis would walk away and call the pup. The helper would only release the pup after a few seconds of pulling.
What I would like to know is what is an appropriate age to start this training and what size harness would be suitable?