Jon Katz quotes
Bites are usually not random attacks by strays. The great majority of biting dogs belong to a family member or friend of the victim. When a young child is the victim, the attack almost always occurs in the family home, and the perpetrator is usually a 'good' dog that had not previously behaved in a menacing way.
Jon Katz
It's natural canine behavior to chew on all sorts of things, roll in other animals' droppings, hump and fight other dogs, menace anything that invades the home. All these behaviors can be curbed, but that takes a lot of work. Trainers say it requires nearly 2,000 repetitions of a behavior for a dog to completely absorb it.
Jon Katz