by Barry B. Burtis D.V.M.
Canine aggression to people continues to be an issue of public concern. Veterinarians who specialize in treating behaviour problems in our pets report that aggression is the most common presenting complaint from their clients. As with most other behaviour problems, aggression is a normal part of a dog's behavioural repertoire. Therefore, it is unlikely that it can ever be totally eradicated. Rather, it is necessary for dog owners to prevent the development of aggression in puppies they choose and hence have a pet that does not threaten the safety of their family or others.
Efforts to accomplish this goal must begin with the selection of a puppy. Owners must remember that the pet they end up with will be the result of nature (genetics, including the breed of the dog) and nurture (a pup's early environment). The purpose for which a breed was developed does still have an influence on their behaviour. A herding breed dog, bred to herd cattle or sheep, is more likely to run after children and nip at their heels than a retriever. A great variety of factors influence an owner's selection of their dog. Behaviour predispositions, I believe, are often not given enough consideration in choosing a puppy. Seeking advice in such a matter must be done carefully. A breeder who has spent a lifetime devoted to working with a particular breed they believe to be the best may tend to downplay or ignore certain negative traits or characteristics possessed by the breed. Pet suppliers, anxious to make a sale, may do the same. Recognizing that anyone may be influenced by personal biases, it's probably best to get this sort of information from a veterinarian, a dog trainer or another independent source.
Two books that I recommend people read for help at this stage of puppy selection are The Perfect Puppy by Hart and Hart and Paws to Consider: Choosing the Right Dog for You and Your Family by Kilcommons and Wilson.
In addition to the behavioural predisposition of the breed, when we get to the individual pup we must remember it has its own genetic controls that will influence behaviour. This genetic makeup also, of course, can be quite variable. This is where puppy temperament testing is used to try and predict a puppy's future behaviour as an adult based upon a series of tests performed prior to adoption, often at 7 or 8 weeks of age. There are different tests that have been developed; however, most try to evaluate a pup's acceptance of restraint, a following test and how a pup responds to certain stimuli. Unfortunately, puppy temperament tests, although popular, are not scientifically validated. This likely has something to do with tester variability and the fact that already by this young age the pup's environment is likely to have impacted on its behaviour and therefore such tests are not truly testing genetic predispositions.
Nevertheless, it is a good idea to spend some time observing a puppy and its behaviour before selection. Eight week old puppies should be willing to engage with human visitors and not huddle with fear in a corner. Think of such a terrified little creature as a 1 on the social comfort scale of behaviour and the dominant little fellow who is first out of the litter to greet a visitor and is immediately chewing a finger with a cute, wee growl and anxious to play as a 10 at the opposite end of the scale. In my opinion, it is best to avoid choosing either extreme as your pet of the future. A pup that shows initial calm, relaxed interest and with encouragement is friendly and playful without being overwhelming in their response may end up being the best pet. Evaluation of the parent's behaviour, if possible, may also be helpful. Good parental temperament does not guarantee the same in offspring but problem behaviors in the parent may well have already influenced a pup.
The sensitive socialization for pups is thought to be 3 - 12 weeks of age. Therefore when selecting a puppy, it is best to ensure that the pup was exposed to proper social experiences in its first weeks of life, both to other dogs (littermates and mother) and a variety of people. While it cannot be said this will prevent all aggression, it is probably the most important thing to protect against its development.