"With no prior warning" is a tough one. Pit Bull Terriers and other bully-type dogs are known to have high prey drives, and you can't really be surprised if one goes after a cat or small dog. I'm pretty tired of both the people who blame the dogs for everything and the people who are trying to convince the world that bully breed dogs are great beginner- or family-friendly pets. Certain dogs have certain traits that you can't train out of them. I love hamsters and rabbits, but I'm not ever going to get one as a pet because my rat terrier has an extremely high prey drive. It's just stupid to put any animal in that situation.

You must be able to control the dog you adopt. Not all dogs are good for every person. Your experience raising dogs, space available, physical strength, and your time should all be considered.

I have heard a good measure for physical strength required is that you should be able to carry any fully grown dog you own. If you can’t pick them up and carry them a short distance you probably do not have the physical stength to handle them.

Yes! And if that dogs keeps being aggressive and attacking and killing innocent pets around the house for several months and then goes and attacks a child or an elderly, you should be held 100% accountable.

Pets are like your children, you're responsible for keeping an eye on them always and to be accountable for what harm they cause to others, unless its truly a one-off case, which it almost never is in all the horrifying cases of dog to human attacks.

Not many can pick up and carry a St. Bernard. However, I agree that one must be able to control one's dog. There is no flexibility there. If you are attentive and diligent you can train the dog without resorting to having to overpower it.

Speaking of overpowering, I used to walk a German Shepherd at a shelter many years ago. He wasn't well trained and in the beginning he used to tug at the leash with all his might. He was rather strong and not being dragged along was a good challenge for any adult human. This was despite the fact that he had only one hindleg. Eventually I taught him to walk without a leash. However, I will never forget him because he demonstrated to me how strong dogs are. It is not hard to exert control over them but if it has to be via physical means, it is not easy.

And I would argue not many people should own a St. Bernard size dog.

However, I should clarify, the point regarding being able to lift a dog that you own is not so that you can physically control the dog in a dominating fashion (I am of the opinion you should not try to dominate a dog as with a large or powerful dog it could end badly). It is more so that if you are walking the dog and it suddenly pulls towards a squirrel or something you are not instantly pulled off balance. Also, if the dog were to be injured that you could get the dog to your vehicle to drive to the vet.

Your point, however, is well taken. Police K-9s may only weigh 50 lbs but easily take full grown men weighing 200 lbs to the ground. No one should try to dominate a dog. That teaches them that that is how you interact with people and they will eventually do it to someone else if not you.

After your clarification, I can see that we are in agreement.

This is a good warning. Whenever one adopts a dog that is not a puppy you have to be ready for anything. You don’t know their past experience or if they were socialized with children or other pets.

Some dogs do have a very high prey drive and may see small animals / children instinctively as prey. Typically this can be socialized out at puppyhood, but for some dogs it may require constant reinforcement. If it is not addressed at puppyhood it may always be an issue and the dog just won’t be suitable to have around babies and small pets.