"In canids and dogs, urination is also part of social communication, representing both an olfactory and a visual signal (posture)."
"The bow is one of the most misunderstood behaviors in canine communication."
We have learned that in order to train a dog we must use positive reinforcement: a dog's behavior leads to a positive consequence = the dog repeats the behavior.
A dog can be stressed by the person holding the leash, or by something that is in the environment: dogs, people, objects, noises, smells...
Dogs do not pull on a leash. Pulling is not a behaviour, it is the consequence of a behaviour.