And in a home outside Philadelphia, this dog runs away after a burglar hurls a plate at it.

So, would your dog come to your defense if a burglar ever broke in?

This is Perry, a five year old yellow lab.

Oh, that's my good girl.

Her owner Michelle Kellaher loves her dog, but she wonders whether Perry would go the extra yard.

I hope she tries to protect me.

To find out, we enlisted guard dog experts Nate Bonilla and Michael D'Abruzzo.

Then, with Michelle's permission, our burglar bursts in as Michelle puts on a great performance as he pretends to assault her.

She screams for Perry.

Perry!

So what does Perry do?

Does she jump in to save her?

Look, she heads for the door.

Michelle is left alone to defend herself.

This is called flight.

Her tail is tucked, she's actually looking for a way out.

Thanks Perry.

I'm a little surprised she almost took off.

Next up, Ruby.

You're a princess, yes you are.

A four year old pit bull lab mix beloved by her owner Kevin Peterson.

I believe she's gonna bite but I'd like to find out.

The so called home invasion goes down, and it sure looks terrifying.

Ruby comes running to investigate.

Ruby get him!

She's not so brave either.

She runs away.

Can you believe she's part pit bull?

Ruby was curious, she was worried about you, but she was not willing to take on the attacker.

Sorry Kevin, but Ruby is a wimp.

My dog failed the test.

Now meet the duo of Frodo and Dobby.

Ferocious looking? Not even close.

Who's a good boy?

They live with Ellen Icamp in West Chester County, New York.

I think Frodo is really gonna go after the attacker.

Well, we'll just see about that.

Ellen puts on quite a show.

And when they hear mom is under attack, the two come running into the room.

Watch as brave Frodo gets right into the mix.

He even jumps up on our burglar and backs him out the door.

They did amazing!

They did amazing.

Mike says Frodo instinctively does a guard dog technique called splitting.

He goes right in between, puts himself in the line of fire and then continues to drive him out.

Little Dobby was just as fearless.

Once they realized that something was wrong they really both stepped up.

I like how they worked together.

Who would have thought the littlest dogs, including a chihuahua, would turn out to be the bravest.