I had a dog who growled nastily at a kid once. I said "no" and it never happened again. In fact he came to like kids and be just great with them. Of course, it wasn't as severe as this sounds.

It may well have worked for you however as we are dealing through the "ether" none of us can adequately gauge the severity of this particular dog's problem and so it is prudent to err on the side of caution for all concerned, including the dog.

Dogs come in many shapes and sizes and with different attitudes, just as owners come with various degrees of competence, experience and understanding; what may quell one dog may be a spark to a flame with another.