In a nutshell, prey drive is that little voice inside a dog's head that says "Omigosh! Lookit that thing moving! GET IT!!"
It's not an either-or thing; all dogs have it, on a sort of varying scale. Some dogs have high prey drive, some have low prey drive, and some are in the middle.
Many working dogs need prey drive to do their job. And that's totally understandable. It makes rounding up sheep, chasing, fetching, tracking, and many other canine activities possible. Skilled handlers use prey drive to their full advantage.
But we're not all skilled handlers with working dogs. I'd say a major portion of dog owners just want a buddy. And if your goal is to have a nice couch potato pet dog that hangs out with you and the family, cruises around town with you, and is generally well-behaved in most situations, then prey drive is not your friend. Not that you can do anything about it except manage it properly.
I got lucky with my last two resident dogs. Felanie was food driven. If it wasn't food, she didn't care. Dozer is ball driven. I think some people might say "Well, it takes prey drive to make him chase the ball." But it's a very ball-specific prey drive. You have to work pretty hard to get him excited about anything else, even a squirrel.
Then came Star. Star has prey drive galore. She's the first for me, really (not counting a Blue Heeler foster dog we had temporarily), and it's taken a bit of adjustment here at home to deal with all the new and curious behaviors that she displays.
She chases any moving thing. She lunges and barks at odd objects and animals. She chases and stares at spots of light on the wall--especially if they're moving for some reason. She bursts out the door into the backyard at top speed, ready to chase any bird or squirrel that might be innocently sitting in the grass. She'll even go bonkers over nothing at all; I often see her staring alertly at a wall, or the carpet, or into space as if she's found a ghost.
Once I finally recognized her high prey drive as the driving force behind all these crazy behaviors, we set about changing routines and procedures so that she had less opportunity for an outburst, and more opportunity to learn self control. Finding a great trainer helped a lot.
Star is not allowed to explode out of the back door anymore. I hold her collar and calmly walk her out to the edge of the deck, then tell her "walk" before I let go of her collar. If she runs, I go get her, take her back to the deck, and repeat until she walks off. She's become much calmer about going into the yard, and I think the birds and squirrels appreciate it.
Star may not bark or lunge at things anymore. She is not allowed to pull towards another dog when she is on leash, no matter for what reason. If she acts inappropriately because her prey drive is egging her on, I stand in front of her and tell her to do a "sit-down" combo three times. This not only gives her an immediate task to focus on, which distracts her from the "prey," but also teaches her that inappropriate behavior nets an undesirable result. She's a very lazy dog and doesn't like doing puppy pushups! Additionally, both the "sit" and "down" positions are submissive and relaxed postures, which puts her in a very different mindset, because prey drive is ramped up when a dog is able to take a more dominant and excited posture.
These are just a few of the steps we've taken to work on reducing Star's prey drive. Though it certainly would be easier if she didn't have much prey drive to begin with, we have the biggest effect on Star's behavior through responsible and careful management and handling. A professional trainer who understands prey drive has been a big help for us in determining the best methods to use to modify Star's behavior.
Star has come a long way since we adopted her. But it's still a little freaky to see her staring wide-eyed at the corner of our bedroom when there's nothing there!