What is the number one killer of young dogs?
Not distemper or parvovirus.

It’s bad behavior.

Euthanasia is the primary cause of death for dogs under age 3, according to the American Veterinary Society of Animal Behavior. And usually the animals are brought in by their owners who can’t control them. So while vets are appropriately concerned about young puppies contracting infectious diseases from other dogs, the society encourages veterinarians to promote early socialization to their clients.

Some vets have been reluctant to suggest animals begin things like puppy kindergarten until the dog’s vaccine series is complete. But in an Oct. 1 article in the Journal of the American Veterinary Medical Association News, the society says socialization classes can begin when the puppy is as young as 7 or 8 weeks old, although they should have one set of vaccines prior to the first class as well as a first deworming.

Dr. E. Kathryn Meyer, the society president, said it’s critical to expose a puppy to other people and dogs before they are 3 or 4 months old. “[Unsocialized] puppies may fail to develop coping mechanisms and grow into dogs that are unable to adapt to new situations,” Meyer said in the article.

So make life good for you and your new puppy. Ask your veterinarian about puppy socialization classes.

Here is the page that includes the society's position on socialization. And go here to find out how to chose an appropriate dog trainer, depending on the behavior issues you are dealing with.