Of course your neighbor has the right to kill his own puppies. Of course that also means he is extremely fucked up by western cultural standards, and you should probably refuse to trade with him or offer him any assistance at all if you wish to discourage his behavior. You have some cultural conditioning that has made you put dogs on a higher level than animals such as cows, however in many Asian countries dogs are routinely raised for slaughter, just as in your country it is quite likely that cows and chickens are raised for slaughter. If your neighbor is a farmer and raises cows because he enjoys killing them and eating them, do you think you have any right to stop him? How about pigs? Pigs are actually quite intelligent as far as non-human animals go, I have heard them compared to dogs in this regard although I am by no means an expert on animal cognition. In India they find it extremely offensive (and I believe it may even be illegal) to raise a cow for slaughter, in much of the western world we place dogs and cats on such a level, however in much of the oriental world they raise dogs and cats for slaughter just as westerners do pigs and cows. In a free society you can kill your cows, chickens, dogs and cats.