I knew a nasty little Pom that bit me twice and sent me to the doctor's office the second time, infection sent me there again for a second visit. On the other hand, I have never been bitten by any large dog I have known. I didn't regard him as mildly annoying. I regarded him as a vicious little menace. Animal control visited his house a number of times as he was often loose in front of his home, ready to take a piece out of anybody who strolled by. When he passed, there was a fairly long list of people with scars who breathed a sigh of relief. A dog like that could hurt a child beyond belief and this little creep bit the face of a child as I recall. If he had been my dog, he would have taken his last ride long before. The thing with the little ones is you don't expect it. At least if you see a large dog you tend to be guarded until you know for sure he's not vicious.
I agree ToscasMom, a dog like this CAN ABSOLUTELY do a lot of damage. I've gone to bite cases where children are left with horrible injuries from small dogs requiring stitches in the face, it's horrible. My automatic recommendation in those cases is to have the dog removed from the home immediately.
I'm not in any way suggesting that a dog (of any size) should stay in a home where there are small children. Aggression rehab requires a structured environment and is dependant on owner compliance, something that is often times not even possible with those kinds of safety variables. I have to be clear as well that most of my cases are by the owners request. I have no problem recommending the removal a dog if I think a child is at risk in those cases either.
I guess what I have a problem with is the fact that so much of this type of aggression is owner caused. Like RD said, little dogs get away with murder and so they learn what buttons to push because those buttons obviously bring rewards. It's not right, it causes huge problems but in the vast majority of these cases, it's correctable..usually with some owner education.
This isn't a matter of me armchair quarterbacking. The OP's description is all too familiar but of course I know nothing about the details. I obviously don't give assessments/advise for aggression over the phone either, but I've been doing this long enough to know how typical this case sounds. As many of you know, I also do not offer "fixes" over this forum but instead find suitable professionals to do the work in person.
My point is simply this. Seeing posts about dog aggression being compared to human aggression and terms like "one way trip to the Vet" being used so freely is dangerous. This is a dog forum and there are many members and even more lurkers. The last thing I think we want to do is provide no other explaination or advise other than to say it's not worth dealing with.
Aggression is frightening, no doubt about it...but 9 times out of 10 it is totally human caused and can be treated effectively and with very little risk to the adult (compliant) owner. I have not had ONE rehab case re-offend in more years than I care to remember.