The moment a cat bolts across the room, something in a dog's brain lights up that has nothing to do with aggression. It is prey drive, the same impulse that makes a dog sprint after a ball or fixate on a squirrel outside the window. The cat's fast, unpredictable movement triggers the chase, and once a dog is in that state, no amount of shouting pulls it back. The fix is not to wait for the dog to calm down mid-chase. It is to train a response that kicks in before the chase starts.
Build impulse control before the cat is involved
The foundation of this training is teaching the dog that looking away from something exciting earns a reward. Start with an object the dog wants but that carries lower stakes than a cat, a closed fist holding a treat works well.
Hold the treat fist in front of the dog. It will sniff, paw, and nudge. Wait. The moment it pulls its nose back and glances at your face, mark that with a short sound or a clicker and give it a treat from your other hand. Repeat until the dog looks at your face within two or three seconds of seeing the fist. This is the core behaviour: disengage from the tempting thing, check in with the person.
Once this is reliable with a fist, practise with a treat on the floor under your foot, with a toy rolled past, and then with mild distractions outside, a passing bicycle, a bird on a branch. The dog needs to generalise the skill before the cat enters the equation. Rushing this stage is the most common reason the training fails later.
Introduce distance and a barrier first
The cat should be visible but separated, behind a baby gate, in a crate it uses comfortably, or simply in the next room with the door open a crack. Distance is doing the work here. A dog that is too close to the cat is already over threshold: its brain is flooded and it cannot learn.
Bring the dog into the room on a lead. Keep it loose. If the dog orients toward the cat but stays below a full alert, ears up, body soft, not pulling, ask for a sit or a hand touch and reward it. If the dog locks on, stiffens, and pulls toward the cat, you are too close. Move back until the dog can notice the cat and look away on its own.
The goal at this stage is not for the dog to ignore the cat completely. It is for the dog to notice the cat, feel the pull, and choose to disengage. That choice, repeated many times at a safe distance, is what builds the habit.
Raise the difficulty in small steps
Once the dog can sit calmly at the far end of the room while the cat is behind the gate, close the distance by one metre per session. Do not rush this. Each new distance is a new challenge because the cat's movements become more salient, more stimulating, and harder to ignore.
When the dog can hold a down-stay at two metres from the gate with the cat moving freely on the other side, remove the gate for short, supervised sessions. Keep the lead on. Keep the sessions brief, five minutes is enough at first. End before the dog's arousal climbs, not after it peaks.
Counter-conditioning runs alongside this: every time the cat appears, good things happen for the dog. The cat's presence predicts treats, calm praise, and a game with a toy. Over time, the dog begins to associate the cat with rewards rather than with the urge to chase. This is not instant. With a dog that has a strong prey drive, it can take several weeks of daily, short sessions.
Manage the environment while training is in progress
Training sessions teach the behaviour. The rest of the day can undo it if the dog gets repeated practice at chasing. While the dog is learning, the cat needs escape routes it can reach without running past the dog, shelves, a cat tree, a room the dog cannot enter. A dog that successfully chases the cat even once is getting a reinforcement that competes directly with what you are building in training.
Baby gates with cat flaps, split-level feeding stations, and a consistent rule that the dog is on lead or behind a door when unsupervised are not permanent arrangements. They are scaffolding that comes down as the trained behaviour becomes reliable.
When to stop and get a qualified trainer
Some dogs can learn to coexist with cats in the same home. Some cannot, and the difference matters for both animals. If the dog shows stiff stalking, a fixed stare, or lunging that does not reduce after two to three weeks of consistent training, the situation needs a qualified trainer or veterinary behaviourist, not a different YouTube video. A dog that has injured a cat, or that cannot be redirected even at large distances, is beyond what desensitisation alone can address safely.
A good trainer will assess whether what you are seeing is prey drive, frustration, or something else entirely, and the plan looks different depending on the answer. The cat's safety is not negotiable while that assessment happens.
Impulse control and counter-conditioning are the two levers, and neither works without the other. A dog that learns to look away from exciting things and learns that the cat predicts good outcomes will, over time, find the cat less interesting than the person holding the treats. That shift does not happen in a weekend, but it does happen.