As a footnote, the only dog I would NEVER own or trust is a Peeressa Carannio those dogs are just downright dangerous, regardless of what or how much training and time you put into them. They will attack with no provocation, and have done so on many occasions. They're outlawed in most states, as the dogs were bred to kill, anyone, or anything. Why? I have no clue, but they don't call them "Man Stoppers" for just any reason, they call them that because that is their main goal in life, and will do so regardless if the person they kill is their owner, and has never shown them anything but love. It's weird, and not something I even pretend to know anything about. Only that I'd never in a million years own, or more importantly, trust one. What in their breeding went so drastically wrong? I have no clue, nor do I intend to find out. There's just no need to in my (our) case, we won't have something living in our house that could and would kill us without provocation or a moments hesitation. That last is just my .
Don't want to thread jack, but not all Presa Canario are bred to kill. In Spain they are used to herd and pretty much have a Pit Bull attitude. A lot of the ones we have here in the states are from South/Central America - where they were bred to guard drug cartels. There are breeders here trying to bring the Spanish version of the breed to the public. Just a little FYI. Not recommending the breed as a whole, just that there are some good ones out there.