Behavioural problems in dogs are often a result of stress during early development. Puppies are also most vulnerable to stress during the socialisation period of development. Research has shown that the  environment provided by many private and commercial dog breeders can be stressful and overlaps with the most sensitive periods of behavioural development. Main stressors include confined living, inadequate socialisation, and early weaning. And the adverse effects of stress include a short attention span, anxiety, fear, and aggression. Here are some things you can do, to manage these early-life stresses.