Pam, I'm sorry but I didn't get to read all of your post. Too long for my attention span. One thing I can tell you is that your small dog will NEVER be 100% safe no matter what dog you get. Dogs are dogs and in the blink of an eye something can happen. It is really up to you. I've known labs that are extremely dog aggressive and Pits that are as dog friendly as can be. You need to make sure that the pack structure is in place and treat these dogs as they are: dogs! My Corso actually got along great with the poodle and not so great with the schnauzer. The actually fought over a a dead lizard in the yard and guess who won? The schnauzer had over 25 stitches and was torn up pretty bad. I would also suggest you get a dog from the opposite sex. My suggestions: - great dane (big and scary. some are good guardians - not protectors) - Bullmastiff (some are very mellow some are very dog aggressive and dominant) - Dogo Argentino (dominant but pack driven so will tolerate other dogs) - DDB (rare ones are athletic and protective) most out there are plagued with problems and won't guard - Corso (could be a good choice) A Corso from good stock should have the stable temperament you look for and the confidence to not care about small dogs. Good Corsos have high prey drive, but if you work with a REPUTABLE breeder that works and temp tests the dogs, you can work to find the most suitable for your condition. One more (hypothetical but very possible) thing, if you get a "guard dog" and he /she gets into a scuffle over food you "by mistake" left out and kills the shi tzu, would you get rid of the big dog? If the answer is yes, then you shouldn't get the dog. Best, ALV