Start by respecting what chasing is
Chasing squirrels is not disobedience, naughtiness or a personal failing in your training. It is the middle of the predatory sequence, the orient, stalk and chase that dogs were shaped by for far longer than they have been pets, and some breeds, terriers, sighthounds and many herding and gundog types, carry it at high voltage. The chase is also self-rewarding in a way few training treats can match: it feels wonderful to the dog whether or not anything is caught, which is why a dog that has chased successfully many times values the behaviour so highly. Accepting this changes the goal. You are not deleting an instinct; you are building reliable brakes, a dog that can notice a squirrel, think, and choose you, plus management that prevents rehearsals of the full-speed version in the meantime.
Management first: stop the rehearsals
Every uncontrolled chase makes the next recall harder, so while training is underway your dog stays on a harness and a long line in woods, parks and any garden a squirrel can cross. Watch your dog, not just the trees: the freeze, the hard stare, the weight shifting forward and the ears locking on are the early frames of the chase, and they are your window to act. Once a dog has launched, your voice is competing with one of the strongest experiences in its life, so all the skilled work happens before that point.
Teach look, then leave: the core exercise
The foundation exercise is often called engage and disengage. At a distance where your dog can see a squirrel but can still turn away, eat normally and respond to its name, let it look for a second or two, then mark the moment it glances back at you, or prompt that glance with its name if needed, and pay with something exceptional. Over sessions, the dog begins to offer the pattern itself: squirrel spotted, look at the human, collect payment. That offered look is gold, because it is the dog making the decision you need at the start of every real encounter. Shrink the distance gradually over weeks, and vary the setting, since a dog that can disengage in your usual park may fall apart in a new wood. Practise a genuinely exciting recall on the long line in these same environments, paying with a jackpot and sometimes with a thrown toy, so coming away from wildlife predicts the best moments of the walk.
Give the chase somewhere legal to go
Instincts that are only ever suppressed tend to leak out at the worst moments, so build sanctioned chasing into your dog's life. A flirt pole, a lure on a rope you move in bursts, lets the dog stalk, chase and catch under rules: the game starts on your cue, pauses when you ask for a sit, and ends with a drop and a trade. Fetch with pauses, searching games where the dog hunts for a hidden toy, and scatter feeding in grass all exercise pieces of the same sequence in ways you control.
Safety, honesty and when to get help
Be realistic about limits. A dog with a long history of catching wildlife may never be trustworthy off lead in squirrel country, and a long line on a woodland walk is a perfectly good lifelong answer rather than a failure. The stakes justify the caution: squirrel chases end in roads, in falls, and in confrontations with cornered wildlife, and in many places chasing protected species carries legal consequences for the owner. If your dog's fixation is extreme, if it cannot eat or respond at any distance from wildlife, or if it redirects its frustration onto you or other dogs when restrained, bring in a qualified behaviourist to build the plan with you. Otherwise, share the plan properly: noting your dog's current safe distance and cues in KinsLe Care Teams means everyone who walks the dog in KinsLe practises the same brakes instead of testing them by accident.