the sensitive period for socialization mean a puppy is more likely to grow up to be a happy, friendly, confident dog. Bad experiences, or simply the lack of positive experiences, may lead to a fearful dog, as we know from classic research from the 1950s and 1960s.13 So it’s really important during this time that puppies are socialized to other safe dogs and to all kinds of people: men, women, children, older adults, people with beards and hats and backpacks and walking sticks, and so on . . .
The developmental stages of a young dog
| PRENATAL PERIOD | Even though puppies are not yet born, there are already influences on their later behavior (see chapter 13 for discussion of the effects of stress hormones crossing the placenta). Prenatal learning can occur: puppies exposed to the scent of aniseed (added to the mother’s food) can recognize it after birth. |
| NEONATAL STAGE: 0–2 WEEKS | Puppies are born with eyes and ears closed. Puppies cannot regulate their own temperature. The mother provides food and initiates elimination by licking. Puppies spend most of their time sleeping, and with their mother and littermates. |
| TRANSITIONAL STAGE: 2–3 WEEKS | The eyes and ears open. Puppies have a startle response. Early motor behavior begins as puppies start to move around. Early social behavior begins and puppies can wag their tails. |
| SENSITIVE PERIOD FOR SOCIALIZATION: 3–12 OR 14 WEEKS | There are many changes during this time as puppies start to learn all about the world around them. Puppies are weaned sometime between weeks 4 and 8 (varies by breed). Motor and social behaviors develop and become more adult-like. Puppies show more interest in people. Dogs learn social behavior through play with littermates. Vaccinations start at 6–8 weeks and continue until 16 weeks (with boosters as required). |
| JUVENILE PERIOD: 14 WEEKS UNTIL 6–12 MONTHS | Although the sensitive period is over, positive experiences during this time are still important as the brain continues to develop. Positive experiences will enable puppies to generalize from experiences during the socialization period. Puppies become more independent. A well-socialized puppy will want to interact with other people and animals. Growth continues (the timing at which it ends varies by breed, continuing longer for larger breeds). The juvenile period continues until puberty. |
| ADOLESCENT PERIOD: 6–12 MONTHS UNTIL 18–24 MONTHS | Post-puberty. Some female dogs can go into heat as early as 5–6 months. |
Sources: Serpell et al. (2017), Bradshaw (2011)14
Puppies are typically adopted at 8 weeks old. Because those early weeks are important for socialization, you should research where your puppy has come from. Puppies that spent this period in a puppy mill or in a barn instead of a house, and then in a cage in a pet store, will have missed opportunities to be socialized (or potentially even had damaging experiences). Ideally, your puppy will come from a home (or a foster home, if a shelter puppy) where good socialization practices have been followed for the best possible start in life.
Pet stores and problem behaviors
Researchers use the puppy from a pet store as a proxy for the puppy coming from a commercial breeder. Studies show that puppies bought from pet stores are more likely to have behavior problems than those acquired directly from a responsible breeder. In one study, published in the Journal of the American Veterinary Medical Association, dogs from pet stores were more likely than dogs obtained from private breeders to be aggressive to their owner, to strangers, to other dogs, and to other dogs that live in the same house. Pet-store dogs were also more likely to have house-training issues and separation-related problems and to be sensitive to being touched.15 Of course, there may also be differences between people who get their puppy from a pet store and people who obtain their puppy from a breeder (as well as in the information they are given).
A study published in the Journal of Veterinary Behavior took some of these owner-related factors into account and still found that 21 percent of the puppies from pet stores showed aggression towards their owner compared with 10 percent of those obtained from breeders.16 Furthermore, this study found that puppies from pet stores had more issues with soiling the house, separation-related issues, and body licking; these particular problems were more common amongst owners who didn’t attend dog training classes, took their dog only for short walks, and punished their dog on returning home. So there is an interplay between where the dog comes from and how the owner treats the dog.
While conditions in commercial breeding establishments vary, some are dire (and that’s probably an understatement). Take a look at the ASPCA web pages on puppy mills to get an idea. Missing crucial socialization opportunities during the sensitive period is one reason for behavior problems later on, according to a report in the Journal of Veterinary Behavior.17 Other reasons are genetic factors (e.g., breeding from animals that are already fearful of people); epigenetic changes due to stress (e.g., the mother being stressed during pregnancy); the puppy being weaned and separated from mom and the rest of the litter at too young an age; the stresses of being transported to the pet store, or being subjected to a restrictive home and/or pet store environment; and a lack of information being given to new owners on how to care for their puppy compared with if they had visited a breeder or shelter.
The only way to be sure your dog has been raised in a good environment is to see that environment. A study published in the Veterinary Record found that when people did not see either the puppy’s mom or dad prior to getting a puppy, the dog was 3.8 times more likely to have been referred for a behavior problem as an adult; if only the mother was seen, the dog was still 2.5 times more likely to have been referred.18
If getting a puppy, make sure you see them with the mom (and be suspicious if the seller suggests meeting at a “convenient” location like a parking lot). Research any health checks recommended for that breed and ask about them. A good breeder—or a good shelter or rescue—will know about the importance of socialization and will be raising puppies in a home environment where they are becoming habituated to the sounds and activities in a normal household, so ask about socialization.
The power of more socialization
A study from the Guide Dogs for the Blind Association in the UK looked at the effects of puppies getting an extra socialization program on top of the existing (already excellent) one.19 Six litters of puppies took part, all Labrador Retrievers, Golden Retrievers, or Lab-Golden crosses. Between birth and 6 weeks of age, all of the puppies received the standard socialization program, and half of each litter also received the additional program. To make sure it wasn’t just time with people that was making a difference, the puppies receiving only the standard program had someone sit with them for the same time as the new program took and interact with them if the puppies engaged with the person.
The new—additional—socialization program took just five minutes per puppy per day in the first week, rising to fifteen minutes per puppy per day in the fifth and sixth weeks. Taking account of what is known about the development of puppies and using resources that are readily available, the program included having a cell phone ring near the puppy; stroking the dog with fingers, with a towel, and with a hand in a rubber glove; and examining the puppy’s ears and teeth. The new program had puppies experience these things on their own, away from the nest and their fellow puppies, as compared with the standard program in which puppies were socialized together. This may have helped the puppies become more resilient to separation-related issues.
The results were striking. At
