Let sleeping dogs lie (or suffer shock consequences)
Sunday, 22 February 2026
ESSAY: There are few more soothing things in life than stroking the dog.
Fingers probing deeply into that dense-feathered neck; those velvet ears softer than any pillow; the lift of the paw and coy head tilt to demand the ultimate tax - a tickle under the arm.
Normally the exchange is entirely positive. He somehow soaks up all my stress and anxiety, in return for the gentle bliss of a stroking hand.
But sometimes, that silky fur bites back.
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It first happened when I lifted him into the car - a frisson of energy spitting at me through that sweet bundle.
Then he’d be lying serene on his bed, and I’d reach for a pat, only to receive a snap of electricity instead.
Or I’d lift his blanket (he’s old, don’t judge) and static would crackle through him, me and that skinny rectangle of fleece.
Sure, I’ve had shocks from car doors, and my hair sprongs into a frizz-ball every time I run a brush through it. But how do you get an electric shock from your dog?
It’s also a new one on University of Waikato senior lecturer in physics, Marcus Wilson.
Well, it’s either you or the dog, he divines.
“What’s the dog doing - is he running around like crazy?” he asks.
Um - my dog is 16, and arthritic. The closest he gets to running around is the remarkable turn of wobbling speed acquired between bed and dinner bowl.
And how can living things conduct electricity anyway?
Physics never came naturally to me, so I dropped it in fourth form. And what little remains in my brain from seventh form chemistry delivers no answers. So it’s back to Wilson.
Remember the atoms that everything is made up of, with their sleepy positive-charged protons in the centre, and negative-charged electrons whizzing around the outside?
Normally atoms have the same number of protons and electrons, Wilson explains.
“Everything cancels out in the electrical sense, and everything’s generally neutral.”
Except that some materials like to shed electrons like my dog sheds hair - transferring them when rubbing against something else.
If you walk across a nylon carpet, those negatively charged electrons pass from the carpet to you in the friction of your footfall. And suddenly your electron and proton balance is out of whack.
“You’re going to end up charged,” Wilson schools. “Then you touch something that conducts electricity really well, like a metal handle of a door, and those negative charges will flow really quickly into the handle, and that creates that little shock that you feel kind of stimulate your nerves.”
Why a nylon carpet specifically (other than the sad demise of Kiwi wool ones)? Synthetic fabrics tend to be more susceptible because of their chemistry, Wilson says. They’re made up of long molecules with chains of atoms, which often allow electrons to move quickly and freely across the chain.
But my dog is not synthetic, and neither am I. He does, however, lie on a fluffy polyester blanket (as I said, stop judging). So as he arcs his back and pushes out those little paws to stretch his creaking limbs, he rubs against the blanket, which transfers electrons.
And apparently I’m a moderately good conductor (salty skin and all that), so when I reach for a pat, that charge pulses into me.
But even natural hair can store or shift charge, Wilson explains. He shares a photo of his son, aged about 2, after trampolining - his fine locks splayed like Doc in Back to the Future.
That’s the bouncing of charge between the trampoline mat and jumper. The hairs become positively charged, and just like the positive poles of two magnets, they push each other away.
“Each hair is now going to repel each other hair, and they kind of separate out to the standing-on-end effect. Hair is a natural thing that will get static charge quite easily.”
I guess they call it a shock of hair for a reason.
So why did I never get static shocks in Wellington, I protest. Same dog, same stroking hand, same blanket-on-beanbag combo.
Chances are that’s because Wellington is damp, Wilson says. Humidity helps disperse static charge, because water is a good conductor.
“So your dog will get all charged up, and then by the time he’s walked from the bed over to you, it’s all dissipated into the atmosphere.”
But what about storm clouds that produce lightning - they’re full of water vapour. And some of the most impressive electrical storms happen in humid places.
Lightning is the ultimate static jolt, and there’s not enough water vapour to diffuse away that much charge, Wilson says.
“Where you have intense storm systems, you have this huge difference between the top of the cloud and the bottom of the cloud, in terms of charge. The electrons end up moving from one to the other, so you have a separation and a huge build-up of electric charge, which discharges as a big spark, either in the cloud itself, or between the cloud and the ground, which is your lightning strike on the ground.”
If you can create electricity from something as simple as two materials rubbing together, that seems like something you should be able to usefully harness.
That’s basically what a capacitor does, says Wilson. It temporarily stores electric charge, and then releases it in a controlled way.
It’s also the basis of the piezoelectric lighters used to fire up gas stoves. When you put the little piezoelectric crystal under pressure, it move electrons from one side to the other, creating a static charge.
And then when they jump back to neutral, they create a spark, which lights the gas.
But surely it’s not great for bits of the world to go around losing their electrons? Apparently some things just like storing up charge, while others like releasing it.
Obviously I prefer cuddles with my dog to be positive, rather than negatively charged. But I’m certainly not about to let sleeping dogs lie.