There are two questions here: One is if a child is bitten by a dog, is it legal for parents to kill the dog? Another question is whether it is legal for dog owners to cause trouble.
In China, there is a legal provision: When people are harmed by lawbreakers, they have the legal right to self-defense in order to protect themselves and their children. This is what people say to each other. For animals, it is self-evident that people have the right to kill a mosquito if it bites you, and you have the right to kill a snake if it bites you. I have never seen a mosquito or snake bite someone and cause a civil dispute, and the court will never hear such a case. So if an illegal dog bites a child and beats it to death, this is worth less than a human being exercising their right to self-defense. Because even if an illegal dog does not bite, people in the community have the right to deal with it or even kill it for the safety of the elderly and children! This is self-evident.
What is an illegal dog? One is an unowned stray dog. One is that although there are people who keep dogs, the owners do not follow local regulations, walk the dogs without leashes, do not wear muzzles, or even let the animals do violence. All three of these are illegal!
So when a child is bitten by a dog, from the standpoint of the victim’s right to self-defense, it is completely reasonable and legal for parents to kill the dog!
The second question is that the dog owner comes to the house to cause trouble. Since the dog-beater's behavior is legal, the dog owner has no reason to cause trouble. The troublemaker is breaking into a house and disrupting citizens' lives. The dog-beater has the right to call the police. State law does not protect illegal property owners. If you keep a dog, it must not harm people, bite people, disturb people, or affect environmental health, otherwise it is illegal. When you keep a dog, you must first wear a muzzle, secondly, wear a leash, and thirdly, bring your own feces bag when walking the dog. Otherwise, it will be treated as a stray dog and it will be illegal. I think illegal dogs cannot be considered legal private property and the state does not protect them.