Stress in dogs, as in us, releases stress hormones in the brain. The effect of this is simply that if any learning can happen, it happens much slower. But the dog is more likely to learn wrong things, such as fear of the situation, or something related to the situation, fear of the person, children or another dog passing by.
There is always some stress in life, but living with dogs, coping with problematic dogs, and training dogs we should be aware of how to keep any stress as low as possible and how to use the natural behaviour of dogs to our advantage in doing this. Also in co-operation with dogs we should know how to get away from stressful situations quickly and calmly – without adding to the stress. It is important that dogs know how to relax and take it easy, even on a busy street (if they live in the city).
This is more beneficial than some tricks. A dog that can relax will live a healthier and longer life.