What would you do when your dog bites your friend?

On Friday I had a very distressed Man ring up to say that his dog has just bitten his neighbour and she had to go to hospital for treatment as there where several puncture marks. Apparently his wife was letting someone through the front gate and the dog got out and rushed forward and bite the neighbour. Now he was asking my advice did he have to euthanise the dog? Legally I do not think you have to, but you know you have dangerous dog on your hands and you could never be sure that it would never happen again. He decided to bring the dog down straight away for euthanasia. He was very upset and I can totally understand why, that would be the hardest things to do to let your beloved dog go because he bite someone. The dog was staffy cross and was happy and relaxed in the consultation room. The man could not decide whether to be present at the euthansia but eventually he decided to be with dog. First time we tried to hold the dog he went to bite me, which made everybody more nervous so we had to put a muzzle on the dog. We then euthanised the dog, checked the heart had stopped and then we helped him carry the dog out to the car, the owner was still very upset. I really felt for the guy but I think he did the right thing.