The Real Reason Your Dog Is Obsessed With Squirrels

My dog has trained me in many ways. I know to fetch him treats whenever he looks up at me with his big puppy eyes, I know to give him a good scratch when he nudges me with his snout. But the most significant adjustment he’s made in my behavior is related to squirrels. 

In my pre-dog life, I never much noticed them darting around town. Now, particularly during our walks, I’m obsessed — I can spot them from yards away, I can hear them squawking and rustling in the distance. I am laser-focused. Why? Well, because my dog is. 

My pup is a mix of many, many different breeds, but somewhere in his genetics lies a deep need to chase little animals. That means I have a deep need to attempt to spot the little animals first and redirect him before he tries to follow one into the road or off of a cliff. But in these moments I wonder — should I, at some point, let him chase a squirrel? Would that be satisfying for him? Would it be safe? And why does he want to so much, anyway? 

To better understand our dogs (and how to keep them safe), I reached out to Dr. Vanessa Spano, veterinary behaviorist at the Schwarzman Animal Medical Center in New York City, for a quick chat about... what else? Squirrels.

Why are dogs obsessed with chasing squirrels?

Dr. Spano says the reaction is deeply ingrained. “Predatory behavior is considered a ‘modal-action pattern,’” she says, referring to a species-specific chain of behaviors that is triggered in response to a stimulus. In this case, that looks like a quick glimpse of a squirrel’s tail. (For those curious, Dr. Spano says another example of a modal-action pattern is a spider building a web.)

In dogs, that chain of behaviors typically unfolds in a set order: orient, eye, stalk quietly, chase, grab-bite, kill-bite, dissect, and finally consume. The sequence is biologically driven, even though not every dog completes every step. “Such behaviors are instinctual and rooted in specific neural circuits in the brain (which dictate our behavior),” Dr. Spano says.

When a dog sees a squirrel, that visual cue activates brain regions tied to emotion and survival, including the amygdala and hypothalamus. Brain chemicals, like serotonin, help regulate how strongly the behavior is expressed.

And breed influences how much of the sequence a dog is likely to show. Border Collies, who were bred to herd, may emphasize eye, stalk, and chase, without the kill. Terriers, who were bred to hunt rodents, may be more likely to follow through. Some dogs show very little predatory behavior at all, something Dr. Spano says is “likely dependent upon genetics and unpredictable until you get to know the dog.”

Even when a chase ends in a kill, which can be dangerous, she says that the drive itself is normal, species-specific behavior, rather than a pathology, like fear aggression.

How do you tell the difference between prey drive and other behaviors?

Speaking of fear aggression! One important distinction, Dr. Spano says, is the difference between true predatory behavior and behaviors that may look similar on the surface, like fear-based aggression.

Predatory behavior is instinctual. It follows the built-in sequence she described earlier, even if some dogs never complete it. That’s different from a dog who reacts aggressively out of fear. A fear-aggressive dog might growl, bark, lunge, or snap at, for example, a child, because the child’s loud noises or erratic movements feel threatening. The goal in that case is distance. Predatory behavior is quieter and more focused. The goal is to pursue, at minimum to chase and grab, and then in some cases to kill.

That distinction matters because fear-based behaviors can often be modified through careful, reward-based training. When a dog is kept below their stress threshold and gradually taught to associate a trigger with something positive, those fear responses can weaken over time. But predatory behavior doesn’t work that way. Dr. Spano compares trying to erase it to trying to teach someone not to pull their hand away from a hot stove. It’s a deeply wired survival circuit.

And what a dog identifies as “prey” can vary. For many dogs, it’s limited to wildlife, such as squirrels or birds. For others, it may include cats. In more extreme and potentially tragic cases, some dogs may target babies or toddlers, drawn to their small size and unpredictable movements. In those situations, Dr. Spano says, cohabitation simply isn’t safe.

Will letting dogs chase “get it out of their system”?

You might hope that if you let your dog chase a few squirrels, their squirrel-chasing urge will fade. But Dr. Spano says that’s not how instinct works. (Sorry.) Because predatory behavior is a modal-action pattern, exposure doesn’t create it, and withholding exposure doesn’t erase it. It “truly is what it is,” she says.

So… should you let them?

From the dog’s perspective, chasing can definitely be satisfying. It taps into an innate need and can provide meaningful mental stimulation.

But Dr. Spano’s concern as a veterinarian is less about psychology and more about risk. If a dog catches and kills a squirrel, there’s potential exposure to zoonotic diseases like rabies or leptospirosis. Beyond disease risk, trainers often caution against letting dogs chase squirrels because the sprinting, sudden stops, and quick turns can strain their joint s and ligaments. Chasing on uneven ground can be especially risky for puppies and older dogs, potentially leading to injuries. Even otherwise healthy dogs are at risk if the ground is rough or slippery.

So, for dogs with strong chase instincts, safer outlets may be the better compromise. “Healthier alternatives may include providing the dog with something safe that smells like a squirrel to chase after, engaging in scent-work, or having them participate in lure coursing, where dogs chase a mechanized, white plastic lure through a field to mimic prey,” Dr. Spano says.