Every dog has breaking points, physically and mentally. Thus, it is wise to set limits as to what stimuli your dog has to deal with…
For example, dogs can sometimes get in a fight with another dog in the home. Maybe the first time, the dogs can once again get along. Sometimes, just that one fight changes one of the dogs so much that it can’t ever get along with that other dog peaceably. Many dog owners contact me after their dogs have been in numerous fights. That makes things much more difficult. On the other hand, my viewpoint is that owners should take even the first incident of hostile squabbling, posturing and competitiveness seriously. Dogs can also freak out if they suffer from separation anxiety, which can further harm the dog mentally, and possibly the dog injures itself along the way. I want to get at the problems “upstream”, and work to help the dogs overcome whatever issues they are displaying, or at the very least, come up with a management plan for the dogs, to prevent further damage.
Dogs also have physical breaking points. For example, I won’t do obedience training on old dogs. Not because they are incapable of learning, but because their bodies are fragile. Simple drills of Sits, Downs, Heeling, Coming, etc. can cause them to get injuries. Puppies also have physical breaking points. I’ve been hired after a puppy was hurt because of rough play, or ham-handed rough training, or negligent supervision. I stress safety in all of the training, to try to minimize physical injuries. It is also why I ask everyone about any medical issues, again to look out for the welfare of the dogs.
We put dogs into complex human environments, so it is up to us to ensure they are safe and happy as we go about our lives together. Once broken, not everything can be fully repaired. It is much better that the dog isn’t broken in the first place.