Different Stages of Development in Puppies
Age (weeks) 3-14. Socialization Period. If socialization later than
14 weeks, (or between 12-14 weeks in some dogs) shyness or aggressiveness may dominate behavior.
Age (weeks) 6-8. Optimum Socialization. If socialization earlier,
shyness often develops, alone with over-dependence on owner, which may lead to over protectiveness.
Age (weeks) 8-10. Fear Imprint. Traumatic, fear producing experiences
maybe permanently impressed causing defensive reactions in some circumstances.
Age (weeks) 12-14. Puberty Onset. Meaningful sexual mounting often
occurs. Males display erections.
Age (weeks) 18-40. Protective-Aggressive. Barking at strangers and
other territorial and social group protective tendencies may occur. Leg lifting may begin in males.
Age (weeks) 35-56. Functional. Many dogs become more serious about
protective-aggressive behavior. A general persistence in behavior problems is noted and corrections become more difficult.
Age (weeks) 104-208. Achievement. Protective -aggressive behavior
can become especially purposeful. Problem behavior appears to become self rewarding, habitual. Corrections markedly more difficult.