Is a nervous Shih-Poo normal?

My female Shih-Poo, just seven months old, is very intellignet, warm and affectionate. She loves most people. Unfortunately, other people threaten her for no apparent reason. She growls at them, wimpers, cries, barks and generally freaks out. She's been though affection obediance training with my wife and responded well. We're baffled at what could trigger such fear. Since you're familiar with Shih-Poos I thought you or someone out there may have a similar issue and hopefully a solution.

 

I had answered your other post. On the old one.
One other thing is, poodles are very one person minded. They get stuck on the one or two people and get very close to them. Very loyal to them. Very smart. Could be that she can sence what others can't. Being a pup, needs reasurance. Poodles are rather cat like too they do what they want if they want too.
I'm just trying to help you understand one of the mixes she mixed with. My other mini poodle wants absolutley nothing to do with other people.