He was a good dog.
We have a Lab mix (looks like a Lab, but too tall and weighs 100 lbs); an Irish Terrier/ yellow Lab mix (hysterical when he stalks squirrels - he is BLONDE and the squirrels see him from when he walks out the back door) and a Cairn terrier/Yorkie mix (She terrifies the chipmunks). They have worked out their pecking order and generally tolerate each other,
There was a lady on the tube some years ago. I think her name was Barbara Woodhouse. Her mantra was ‘no bad dogs’.
She was right. Dogs become what we train them to be.
I am sometimes uncomfortable with folks who disparage American Staffordshire Terriers (I think that's the official name for pit bulls.) I've met some who are real mushes, and others that are nasty. But we could say the same about Yorkies or Poodles.
I guess it is just how we teach them to behave.
Because of selective breeding, a dog of a particular breed will start with a set of instincts and abilities that are hard wired into him.
My older Lab never saw a duck until she was over 3 years old. Before that she was an obedience and agility dog. The very first time she saw a duck fall out of the sky, she knew what to do. It was in her breeding (thank goodness -- her daddy was a show dog, an affable sort but wouldn't know what to do with a bird if you handed it to him. But her mama was a daughter of the only Chocolate Lab ever to win the National Field Trial title.) It was like magic -- all we did was refine her natural instincts. Even though she started very late for a retriever, she's a very good one. She'd be better if I were a better trainer!
On the other hand, there are some folks with Standard Poodles who belong to our retrieving club. Poodles were in fact hunting dogs once upon a time, but it was hundreds of generations back and most of the desire to hunt has been bred out of them. Their owners are trying really, really, really hard -- but it's like trying to push a rope uphill. The dogs are intelligent and obedient, but you can see when they go to the line that they are fetching the bird or bumper because they were commanded to do so -- contrast that to a Lab that you have to train to WAIT until you give the word to leave the line, that will go through flooded timber and waterweeds and heavy cover because every cell in their body is focussed on retrieving that duck!
It's not true of every dog -- there are well bred Labs who just don't have the hunting instincts -- but by and large Labs will hunt, Terriers will dig and chase vermin (and bark), and Border Collies will herd anything that moves. And yes, they are VERY smart -- all those generations of handling sheep in close cooperation with their masters. BCs pretty much rule Agility, and my little Lab is a dark punctuation mark in a sea of black-and-white BCs in the Masters class.
AmStaffs are a touchy subject -- I believe once again that it's part training, but the dogs were originally bred for fighting. They aren't generally people-aggressive because their handlers were down in the pit with them, but they are hard wired for dog-aggression. Obviously not every AmStaff is dog-aggressive, but it's something that you have to be ready for and watch for, and train the dog to absolute obedience. Not a dog for casual ownership -- Labs and Goldens are better for that. Most of them are naturally mellow and they've had dog-aggressiveness bred out of them because of hunting and handling in close proximity to other dogs.