What a puppy experiences in its early days shapes it for life.
Puppy mills are designed to encourage female dogs to produce as many puppies as possible. Often, loving human contact is lacking. This can have lifelong consequences for the animals.
Experiences in childhood shape a dog – this is also true for dogs. Neglected or abused puppies and young dogs may develop into animals more prone to anxiety and aggression. This is particularly true for certain breeds, such as the American Eskimo Dog, a spitz-like breed standard in the USA.
This can become a problem, for example, when people acquire a cheap puppy from Eastern or Southern Europe, bred under appalling conditions. Such animals, often marketed online as supposedly rescue dogs, frequently come from puppy mills and usually suffer lifelong deprivation of proper imprinting and socialization, as animal welfare experts warn. Many of these animals with behavioral problems ultimately end up in shelters. For adequate socialization with humans, a dog must have positive interactions with people, especially during its first few weeks of life.
Dogs undergo a crucial phase of rapid physical, behavioral, and cognitive development during this period, as researchers led by Julia Espinosa of Harvard University in Cambridge, Massachusetts, explain. Disruptions to these processes due to poor rearing conditions or insufficient maternal care are considered causes of later behavioral problems. Inconsistent or overwhelming social interactions are also a possible cause.
Reactions included snapping, retreating, or hiding.
Previous studies had already indicated that traumatic experiences in early puppyhood promote anxious or aggressive behaviors, writes Espinosa's group. The current findings are based on a survey of owners of more than 4,000 dogs from 211 different breeds. One-third of the dogs had experienced adversity in their first six months of life, including abuse, neglect, and serious injuries.
The study also recorded the animals' reactions to 45 common triggers of aggressive and fearful behavior, including sudden, loud noises or strangers approaching the front door. Typical reactions included snapping, biting, retreating, or hiding. Animals that had experienced unpleasant events in their first six months of life showed significantly higher levels of aggression and fear as adults. Other factors, such as sex, age, and neutering status, also played a role, but their influence did not outweigh that of the negative experiences.
Some breeds are more resistant to stress.
Dogs of breeds like the Labrador Retriever seemed relatively unaffected by adversity during puppyhood regarding later aggressive behavior, whereas a clear correlation was found among representatives of other breeds. These included the American Eskimo Dog, American Leopard Hound, and Siberian Husky. According to the researchers, this suggests that hereditary factors play a role in determining a dog's sensitivity to negative experiences in its early years. Some breeds possess an innate higher resilience to stress.