Sensitive Periods of Development
In 1945, studies at the Roscoe B. Jackson Memorial Laboratory began to determine the relationship between heredity and social behavior in dogs. These studies led to the stages of development that are widely recognized today – the neonatal period, the transition period, the socialization period, and the juvenile period. In addition, further studies have added a fifth period defined as the prenatal period. (Serpell & Jagoe, 1995, p. 80). Each of these stages is a period of time when puppies are particularly sensitive to environmental influences. The two additional stages of adulthood and seniorhood are not considered sensitive periods, just stages of life.
The prenatal period is the time before birth, where unborn puppies may be influenced by the impact of stressful events upon the mother. This is most likely caused by maternal corticosteroid hormones that can directly affect the development of the fetus’ physiological responsiveness to stress. (Serpell & Jagoe, 1995, p. 80) In studies of both rodents and primates, evidence shows that prenatal stress can impair stress-coping ability, and is able to cause a disruption of behavior in aversive or conflict-inducing situations in juvenile and adult offspring. (Braastad, 1998) Therefore it is important whenever possible to reduce the stress of the mother during the prenatal period in order to increase the stress-coping abilities of the unborn puppies.
The neonatal period is the time between birth to approximately 2 weeks of age, when the puppies are helpless, and dependent on the mother to survive. They are incapable of seeing or hearing, but they are sensitive to touch and certain tastes and possibly smells. At this age, puppies are only capable of learning simple associations, and those are believed unlikely to carry over to later periods. However, it has been shown that there are long-term effects to a puppy that is handled daily during this time, including accelerated maturation of the nervous system, more rapid hair growth and weight gain, enhanced development of motor and problem solving skills, and earlier opening of the eyes. (Serpell & Jagoe, 1995, p. 81). Exposure to varied stimulation in the neonatal stage may also produce more confident and exploratory behavior later. (O’Heare, J. 2007) It therefore appears beneficial to provide short periods of daily handling to puppies during the first two weeks after birth.
The transition period, is in many ways a continuation of the neonatal period. It includes from the time the dog’s eyes open at 10-16 days, to the time the ear canals open approximately one week later. During this time, many new behaviors are demonstrated, such as movement by the puppies both forward and backward, standing and walking, and even possibly play fighting. During this time, they begin to show interest in solid foods, they begin voiding on their own and they begin to develop communication signals. For the first time, they retain learning long-term, and they begin to prepare for the socialization period.
The socialization period begins at the end of the transition period, around 2 ½ to 3 weeks of age, and continues until between 9 and 13 weeks of age. The socialization period has been defined as the critical period for the formation of primary social relationships or social attachments. This period of time tells a puppy who its future social partners will be, as well as the species to which it belongs. (Serpell & Jagoe, 1995, p. 82). Studies have shown that it does not take very frequent or prolonged social encounters to achieve adequate socialization – even 5 or 10 minutes of human contact, once or twice a week will accomplish this. During the socialization period, puppies will form attachments not only to other creatures, but also to particular places – termed site attachment by Serpell & Jagoe (1995, p. 82). If puppies are not handled by humans during this socialization period, they remain fearful of humans and intractable even after many weeks of handling and petting. Likewise, a puppy that is taken from its litter and raised with no contact with other dogs during this socialization period will often have a hard time interpreting communication signals when it does meet other dogs in the future. It may also prefer to bond with whatever creatures it was socialized with instead of creatures of its own species. For example, a puppy that is raised with other kittens during this time but never meets another dog, may in the future prefer to spend its time with kittens even when given the option of spending time with other dogs instead.
At around 8-10 weeks of age, puppies enter their first “fear period”. This is a time when puppies become hypersensitive to distressing stimuli, and fearful events can cause long-term consequences. For this reason, it is important to limit stressful events as much as possible during this time.
At the end of the socialization period, the juvenile period begins, and continues until approximately 6 months of age, when the dog reaches sexual maturity. The juvenile period begins gradually, and there is no clear-cut delineation between the socialization period and the juvenile period. According to Coren (2004, p. 162), dogs that appear to be more wolf-like, with longer narrower faces and pricked ears, seem to have more sharply defined socialization periods, while dogs that are more puppy-like, with shorter faces, large round eyes, round head, and floppy ears, seem to have longer socialization periods that don’t end abruptly. During the juvenile period, a dog’s social behaviors begin to take on adult form. This period is a time of gradual change that chiefly involves the maturing of motor capacities. (Scott & Fuller, 1965, p. 111)
From the beginning stages of prenatal through neonatal and the transition period, puppies can be influenced through their mother’s hormones, touch, and eventually vision. But it is not until the socialization period, and then the juvenile period which follows, that social relationships are really developed, both with other dogs and with humans. The experiences that a puppy has during the socialization and juvenile periods will affect how they perceive their world for a very long time, and it can be difficult to overcome the learning that takes place during this period of time.
References:
Braastad, B. (Dec 1998) Effects of prenatal stress on behaviour of offspring of laboratory and farmed mammals. Applied Animal Behaviour Science. 61(2), 159-180.
Coren, S. (2004) How Dogs Think. New York: Free Press.
O’Heare, J. (2007) Aggressive Behavior in Dogs. Ottawa: DogPsych Publishing.
Scott, J., Fuller, J. (1965) Genetics and the Social Behavior of the Dog. Chicago: The University of Chicago Press.
Serpell, J., Jagoe, J. (1995) The Domestic Dog: its evolution, behaviour, and interactions with people. Cambridge, UK: Cambridge University Press.
