Not too long ago, one of my friends mentioned that the she had heard about problems at a dog park. It seems that someone was bringing an aggressive dog who was trying to pick fights with the other dogs. The people who brought their dogs regularly to the park were up in arms. Talking to the aggressive dog’s person was proving to be useless, because his attitude was that dogs should be able to work these things out among themselves, and he was not going to intervene in something that he saw as normal dog behavior. The owners of the smaller dogs were particularly terrified. The aggressive dog was big and could potentially hurt a little dog. No one knew what to do to solve this problem.
I mentioned that I have seen such dogs before. In my experience, a dog who is aggressive toward other dogs has not be socialized properly. This often happens when people get a puppy who is 4-5 weeks old, before the puppy has had a chance to imprint on other dogs.
Imprinting is a form of learning that happens at an early age and lasts the lifetime of the animal. The first person to thoroughly investigate the imprinting process was the Austrian ethologist, Konrad Lorenz, who won the Nobel Prize in 1973 for his contributions to animal behavior. Imprinting takes place during a relatively brief period of time called the sensitive period, after which the information learned during the imprinting process either cannot be or is very difficult to reverse.
Lorenz found that ducklings and geese have a sensitive period shortly after hatching, where they respond to visual and auditory cues by following whatever object that is making sounds. Usually that is their mother. In ducks and chickens, this sensitive period is somewhere between 12-48 hours after they hatch. Through this kind of imprinting, birds learn who their mothers are, and ducks, geese, and quail learn to follow their moms.
The following response is not limited to birds. Imprinting has been shown in a number of mammals as well. The nursery rhyme, “Mary had a little lamb/Its fleece was white as snow/And everywhere that Mary went/The lamb was sure to go,” describes a lamb who was imprinted on Mary.
But another important feature of imprinting is learning what species an animal belongs to, and who to mate with in the future. This phase of imprinting is sometimes known as sexual imprinting. Among social animals, the imprinting tells a young animal not only who its future mating partner is likely to be, but also who to socialize with when the animal starts to grow up.
With birds, such imprinting can be a problem when someone takes a young bird out of a nest and the youngster imprints on humans. I know a person who rescues birds. She has a turkey vulture that she cannot release back into the wild because the vulture imprinted on humans at an early age, apparently because someone took him out of his nest and raised him. Now the vulture thinks that he is human, and directs his courtship behavior at people instead of at vultures. Vulture courtship behavior includes, in part, regurgitating the rotten food that he has eaten at the feet of his intended beloved.
Dogs go through an imprinting process too. In dogs, the sensitive period lasts roughly between a puppy’s 4th and 12th weeks of life. During that time, puppies learn who their mother is, and also learn about future mates and their social group.
If a puppy is taken away from her mother at week 4 or 5, she does not have a chance to imprint on dogs as social partners. She does imprint on people, and subsequently thinks of herself as a person rather than as a dog. So when she is placed in the company of other dogs, she has neither the social skills to know how to interact with them, nor even very much interest in going through dog greeting protocols. She sees herself surrounded by alien beings, and responds aggressively.
Fortunately for the dog-human bond, dogs can imprint on both dogs and people during the sensitive period of imprinting. If a dog is allowed to be with his mother and littermates from about week 4 to about week 8, he will imprint on dogs and will learn dog social skills. If the dog is then placed in the company of people during weeks 8-12, he will imprint on the people that he sees around him.
While the effects of imprinting can sometimes be reversed, it takes a lot of work. A dog who was not imprinted on other dogs at an early age can be socialized, but it requires a lot of patience and effort on the part of the dog’s people.
A much better solution is to let puppies imprint on other dogs at an early age, and only take them away from their mothers and littermates when they are around 8 weeks old.