The Guard Dog Test

By Erika Von Tiehl

PHILADELPHIA (CBS) - Dogs can seem pretty ferocious with their barking and growling when someone comes to the house.

But would your dog race to the door, ready to stop an intruder?

Would he respond like a trained k-9 dog?

Charlie, a trained K-9 with the Delaware County Sheriff's Office, was ferocious demonstrating his suspect apprehension skills recently during a training session.

But is your dog all bark and no bite?

To find out 4 families let us put their dogs to the test.

The roster includes Jake, a German shepherd with a scary reputation, Rocky, another German shepherd and Mason, a Springer spaniel.

And in another home we have 2 dogs.

They are Jameson, the bulldog, and Cain, a boxer.

In each home we set up 7 cameras.

Then we asked Corporal Bob Adams from the Delaware County Sheriff's Office to pretend he was an intruder; first, in an empty house and then with someone home.

We start out with the dynamic duo of Jameson and Cain.

So what will Jameson do when the corporal comes in to the house?

"I think he might go at him a little bit," says Jameson's owner Rob. "I think Cain will just be like 'hey, come on over, pat my belly.'"

Adams goes in and Jameson barks and makes a racket.

But then along with Cain, the pair only sniffed our intruder as he made himself comfortable.

And what will happen when the corporal comes in with Rob and his fiancée in the home.

"I think he'll be a lot more aggressive, especially if he comes towards one of us," says Rob.

His fiancée disagrees.

Turns out while our corporal play acts by hitting the two people, the dogs run around but don't bite.

"He was all bark and no bite," says Rob. "Big chicken."

Next is Mason, the Springer spaniel.

"He can steal the food off the table sometimes," says his owner Michelle.

Mason does quite a bit of barking as Adams enters the home, but the only thing he takes a bite out of is a dog biscuit that Adams tosses to him from a box he found on the kitchen counter.

Later with Michelle and her sister in the house Mason barks as Adams enters.

The dog becomes agitated and growls as Adams pretends to then push the women around.

Michelle is pleased with Mason's reaction.

Time for Rocky.

The German shepherd looks pretty tough to anyone standing outside the front door.

"He's gonna bark, then jump all over him and then probably look for a ball to play with," predicts his owner, Paula.

And she was right.

Rocky sounds the alarm as Adams reaches the front door but then tails him around the house.

And it isn't long before Rocky picks up the ball and is ready to play.

With his owner home, nothing again.

Rocky had no fight in him at all!

Then there's Jake.

"He does a pretty good job of scaring the postman and the UPS guy away," says his owner John who is pretty confident in his dog.

"He's going to do whatever he can to protect the house," says John.

A barking, snarling Jake meets Adams as he comes inside.

But once Adams is in the house Jake leaps away and keeps his distance and manages a small bark.

The worst thing he did was knock over one of our cameras!

"I guess no extra dog biscuits in the dog bowl today," John said.

He was disappointed again with John's wife in the house.

The scary German shepherd was a pussycat.

In the end none of the dogs attacked our intruder.

Why?

Corporal Adams has a theory.

"I have no fear, the bad guy's going to have fear, once they sense fear you're done," he said.

And even if dogs don't attack, Adams says they will alert you with their barking if an intruder is nearby.

That's when you call 911 and maybe K-9 Charlie will be one of the responding officers.