SHTF and you will be happy to have big dogs. Little ones can only warn you, and typically will at every opportunity, even if there is nothing to be warned about.

I'd never have a husky for a shtf, shepherd yah, any of the guarding dogs.. kangal, pyrenees, komondor, etc., but they have their own drawbacks in a non shtf environment. A g shepherd dog is a happy medium.

You really need to grow a puppy with livestock for them to be safe for the livestock.