Dogs cannot do what they aren't designed to do.
You'll get one-off dogs in any group, but very few breeds can consistently do protection work.
Chihuahuas aren't one of them.
No trainer who knew anything about protection training would work with a Bassett.
They're hounds, not working dogs. They track and trail- that's it.
There's a reason breeds are grouped by purpose; herding, working, hound, sporting, etc.
To do protection work requires three drives to be present in the dog, at the right degrees and with the right balance to one another. Prey drive, defense drive and fight drive.
Those are just to train a dog to bite and fight a man.
To teach him to do it under your direction, and be controllable throughout requires a high degree of biddability.
Very few breeds of dogs have all of those elements present.
Even in the breeds that DO have them, maybe every 1 in 100 will actually have it.
After that it will take 2-5 years of intense (7 days a week) training to develop those skills until you have a well-trained dog.
German Shepherds, Dutch Shepherds and Belgian Shepherds are really the only three breeds that are "all-purpose".
They can, and do, compete at high levels in virtually every form of dog sport there is.
Agility, herding, fly-ball, Schutzhund, Ring Sport, hunting, sledding/skijoring, Police Service, Military Working Dogs, Search and Rescue, cadaver detection, Service Dogs, the list goes on and on.
If you need a dog for a very narrow range of duties, you go to what it was bred for.
Need a prisoner take-down dog? A Rottie would be great.
Need a dog that can take down a prisoner in a cell, and track him for 15 miles if he escapes, and detect drugs in the cell? Get a GSD.
Need a dog that can do anything? Get a GSD.