But He's Never Done That Before!

It's one of the hardest phone calls I've received.

A client contacted me after their dog had grabbed the family cat. The cat had rushed past, the dog chased, caught it, and bit it. Thankfully, the cat survived, but everyone was devastated.

The first thing they said was, "I don't understand. He's always been so gentle."

I believed them because I knew the dog they were describing. He was affectionate, lived peacefully in the home, happily accepted pats from strangers, loved curling up on the couch, and had never shown what most people would describe as aggression.

So what happened?

The answer lies in something many dog owners misunderstand: prey drive.

The term gets thrown around a lot, particularly when talking about greyhounds, terriers, herding breeds, and other working dogs. Somewhere along the way, prey drive became synonymous with aggression, dominance, or having a "bad" dog. In reality, it is none of those things.

Prey drive is an instinctive behavioural system that evolved long before dogs became our companions. Wild canids relied on it to survive. If they couldn't locate, pursue, catch, and consume prey, they simply didn't eat. Although our pet dogs no longer need to hunt for survival, selective breeding has preserved different parts of that behavioural sequence depending on the jobs humans wanted them to perform.

A Border Collie was bred to control movement. A Labrador was bred to retrieve. A Jack Russell was bred to pursue vermin. A Greyhound was bred to visually detect movement, accelerate with extraordinary speed, chase, and catch. Each breed carries different pieces of the same behavioural puzzle, which is why prey drive doesn't look the same in every dog.

One of the biggest misconceptions is that prey drive simply means a dog likes to chase. Behaviour scientists describe predatory behaviour as a sequence rather than a single action. It often begins with orienting to movement. The dog notices something. Their eyes fixate, their ears change position, their body becomes still, and their attention narrows. Depending on the dog and the breed, this may be followed by stalking, chasing, grabbing, biting, and, if uninterrupted, the final stages of the sequence. Selective breeding has exaggerated some of these behaviours while reducing others.

This is why one dog may quietly freeze and watch birds from a distance while another explodes into pursuit the moment something moves.

One of the questions I hear most often is, "But he's fine with cats."

My response is usually, "Fine doing what?"

Sleeping beside them? Living in the same house? Walking past them while they're lying still?

Those situations tell us very little about what might happen if that same cat suddenly sprints across the backyard. Movement changes everything.

This is also why these incidents catch owners completely off guard. Most people expect aggression to come with obvious warning signs like growling, snarling, or raised hackles. Predatory behaviour often doesn't look like that at all. Many dogs can go from quietly resting on the couch to full pursuit in a fraction of a second. To the owner, it feels as though the behaviour came out of nowhere. In reality, the instinct was always there. It simply hadn't been triggered in that particular context before.

When a moving object activates that behavioural system, ancient neural pathways take over. The chase itself becomes highly rewarding because the brain releases neurotransmitters that reinforce seeking and pursuing. That is why prey chasing is so difficult to interrupt once it has started. It isn't because your dog is choosing to ignore you, because they suddenly don't love you anymore, or because your recall has disappeared overnight. It's because biology has temporarily become louder than your training.

Does that mean training is pointless?

Not at all. Understanding prey drive actually gives us a much clearer training plan.

We can build engagement until checking in with the owner becomes second nature. We can develop an emergency recall long before wildlife appears. We can teach pattern interruption cues, strengthen impulse control, and create a long history of reinforcement for choosing the handler over the environment. Long lines allow us to prevent rehearsal because every successful chase strengthens the behaviour, while structured outlets like flirt poles, retrieve games, and scent work allow dogs to safely express parts of their natural predatory sequence.

Just as importantly, we manage the situations our dogs are not yet capable of handling. Management is not an admission that training has failed. In many cases, it is the most responsible training decision we can make.

There is one final point that deserves honesty.

Some dogs will never be trustworthy around small animals. That doesn't make them dangerous, aggressive, or bad dogs. It simply means the consequences of getting it wrong are too great.

As trainers, our responsibility is to improve behaviour as much as possible. As owners, our responsibility is to recognise that genetics still matter. The most successful owners aren't the ones who pretend instinct doesn't exist. They're the ones who understand it, respect it, and build a life where both their dog and the animals around them can remain safe.

Sometimes, loving your dog means accepting who they are rather than expecting them to become something they were never bred to be.

"Nature is cruel, but we don't have to be."

— Temple Grandin