Have you ever seen this before, the way the dog reacted?

Such dogs may react to any and all stimuli only if ordered to do so.

The big dog was reacting to the noises in the wall they had both been hearing for the last two hours.

If he'd just pretended to throw a stone, our courageous dog, friend of man, would have reacted the same way.

"I don't know, Iain, but when dogs react like that in the middle of the night it's always because they heard something."

I had ordered a test run to see how the dogs would react.

The dog reacts to a ringing telephone and tells his mistress.

It was unclear last night what the dogs were reacting to in the bags.

There, a second bomb-sniffing dog also reacted to the trash can.

The dog reacted to the name again, lifted its head, gazed about wistfully.