Check-cord tension is one of the most important forms of communication between your dog and you. How much tension is too much, or to put it another way, how hard should a dog pull is a question that is often asked but hard to answer. It is like asking a race car driver how fast is too fast. It depends on the car and the track. Same thing with a dog. It depends on the dog and the situation.
I am sure you have seen amateur trainers dragged around the training field by their dogs. In these scenarios, dogs are telling trainers they do not respect them. Dogs that pull with enthusiasm without dragging trainers around are showing respect, and dogs that walk on loose check-cords without pulling may be unhappy about going to the field. I had a situation like this a few years ago. I was working a young dog and teaching him to be steady. One morning, I noticed he was not pulling as hard as he normally did. Right there, I knew I had a problem so I watched him closely as he worked birds and noticed he had lost some of his intensity on point. Because I paid attention to the lack of check-cord tension, I was able to step back in training, shoot a couple of birds for him, and before long, he was pulling with enthusiasm to get to the field.
This spring I was working another dog. He was broke on pigeons and had progressed to quail. He had pulled with enthusiasm on pigeons, but now that he had gone to quail, he started dragging me around the field. I was slow to realize how hard he was pulling and that quail were getting him too amped up. As a result, he had lost his manners and reverted to busting birds again. If I had paid closer attention to what he was communicating to me with the check-cord, I would have stopped working him on birds and focused on gaining his attention. A few sessions of asking him to go with me and come to me on the check-cord would have done wonders to regain his respect and get him focused again.
A basic check-cord is about 12-ft. long, and while it may appear to be a simple piece of rope with a snap at one end, it is the most complex piece of training equipment you will own. For many pro-trainers, it is the one piece of equipment they cannot do without. Check-cord tension is where much of the communication between your dog and you takes place. Learning how to read this tension and understand what the dog is communicating takes practice and experience. You will have a lot of dogs on the end of a check-cord before you get good at it, but if you pay attention to the tension, it will help you figure out what is going on in your dog’s head.