If you have a dog, you've likely found yourself in this position: You're on a walk together, they sniff out a seemingly great spot to use the restroom, then proceed to spin in anywhere from two to 10 circles before they finally get down to business. While this seems strange and maybe even straight-up nonsensical to us, there actually is a very good reason for why they do this, according to researchers.
This isn't a new study, but it does answer an age-old question that every dog owner has surely asked at some point: Why does my dog spin before they poop? According to a 2013 study published in Frontiers in Zoology, a team of Czech researchers discovered that canines do this because, like many mammals, they prefer to align their bodies in accordance with the Earth's north-south axis when they excrete.
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That's right—dogs spin before they poop because of the Earth's geomagnetic poles.
Dogs poop with magnetic alignment
We already knew that dogs can use the magnetic field to navigate, but it turns out they rely on it for other things too. To conduct this study, researchers worked with 70 dogs of 37 different breed types over a two-year period. During this time, researchers observed nearly 2,000 defecations and over 5,000 urinations. Amid these bathroom breaks, they measured when dogs circled, which direction they circled, and where they finally landed before pooping or peeing. At the same time, researchers also use magnetograms to measure changes in the Earth's magnetic field from outing to outing. In measuring down the dog's bodies along the thoracic spine, the team found that the dogs preferred to use the bathroom while their bodies were positioned in alignment with the Earth's north-south axis, and during calm magnetic field conditions.
Do dogs really poop facing magnetic north?
Yes! Dogs really do poop facing magnetic north. At least, when the magnetic field is calm. When the magnetic field is unstable, dogs don't align themselves with the north-south magnetic poles. Interestingly, the study revealed that adult dogs aged 2 1/2 to 7 years of age preferred defecating in a north-south alignment over puppies and senior dogs, who didn't always prefer to poop this way even under ideal conditions. It's not yet known for sure why they position themselves this way, but one possibility could be that it's related to their homing instincts, which allows them correctly return to safe territory.
Here are some other questions you may have about dogs and magnetism.
What is magnetoreception?
Magnetoreception describes the ability to detect the Earth's magnetic field. Homing animals, like birds, rely on this behavior to fly south for the winter and find themselves back home once the weather warms up. Changes in the Earth's magnetic field through occurrences like magnetic storms can be detected by magnetoreception, and for the first time, domesticated dogs have been shown to possess this trait.
During the study, researchers didn't notice any preference for pooping direction based on things like the dogs' sex, age, or breed. They only noticed a pattern emerge when they organized their data by the conditions of the Earth's magnetic lines on a given day, and saw that the dogs excreted once their bodies were in north-south alignment when the magnetic field was calm.
How do dogs find the Earth's magnetic field?
In short, they are born with it! In addition to birds, dogs naturally possess homing abilities, much like wolves, red foxes, and coyotes. Wild canids rely on this ability to find their way back home after long hunts or during other roaming behaviors, which is done with the help of magnetoreception. Thanks to this study, it's now been shown that domesticated dogs possess magnetoreception as well, hence, pooping north to south when they can detect a calm magnetic field.
To keep the study truly neutral, the research team even had the canines eliminate off-leash in fields away from their homes or kennels so there was no chance of forming favorite spots to pee in, and placed them away from roads, high-voltage power lines, and steel construction.
What is the Earth's north-south axis?
The north-south axis, otherwise known as the rotational axis, is an imaginary line that runs through the Earth from north to south. The ends of the axis are known as the north pole and the south pole. This axis is what allows the Earth to rotate, and many mammals are aware of the magnetic field that surrounds us. It also helps those living in the animal kingdom, ourselves included, to measure location. This is particularly helpful for dogs, who were once roaming animals before becoming mostly domesticated.
Why do dogs go around and around before they poop?
Dogs spin before pooping to correctly align with the Earth's axis. However, not all dogs do this, and no dogs do this when the magnetic field is unstable, so what's the explanation the rest of the time? Some dogs may circle while searching for the perfect spot to pee or poop, which they do with the help of their noses. In following this scent trail, they may be led to walk in circles. Alternatively, some dogs may circle to spread their own scent around, being the territorial animals that they are.
Are dogs affected by magnets?
According to a 2018 study, yes. At the very least, they may be ably drawn to magnets thanks to senses other than their impressive sense of smell. In the study, researchers used operant conditioning to have dogs locate a bar magnet, and a food treat. In most cases, the dogs were able to locate the magnet without using their sense of smell, or relying on visual cues from their handler, yet were only able to find the food treat when they were able to smell it.
Could this be why so many dogs tend to eat refrigerator magnets? It's not certain, although due to the general weakness of these magnets, it's unlikely. Ingesting magnets can, however, be very dangerous to dogs, so be sure to keep yours out of reach, or possibly remove them from the home if you have a canine companion who likes to pick things up off the ground.
The bottom line
The reason some dogs spin before they poop is because they are aligning their bodies with the north-south axis of the Earth. Calm conditions within the field produced the most consistent alignment, especially among adult dogs. Variations in the intensity of the Earth's magnetic field produced a decline in alignment among dogs, which supposes the idea that dogs do possess magnetoreception.