Do dogs face north to poop? The magnetic-field study, explained honestly

The paper is “Dogs are sensitive to small variations of the Earth’s magnetic field” by Vlastimil Hart, Hynek Burda and ten colleagues from the Czech University of Life Sciences in Prague and the University of Duisburg-Essen in Germany. It was published in Frontiers in Zoology on December 27, 2013.

Over about two years, 37 dog owners and their helpers in the Czech Republic and Germany walked 70 dogs of 37 breeds off leash in open fields, away from roads, power lines and steel structures. Each time a dog relieved itself, they recorded which way its body pointed with a hand-held compass. That came to 1,893 defecations and 5,582 urinations.

Burda’s group had already reported that cattle and deer tend to stand north–south while grazing or resting. Dogs were a convenient next test: they are everywhere, and they hold still at a predictable moment.

Not exactly, and not always. When the team pooled all the poops together, the directions were highly scattered: there was a faint north–south lean, but nothing you would notice on a walk. A clearer pattern only appeared after they sorted each walk by how stable Earth’s magnetic field was at that moment, using records from geomagnetic observatories.

When the field was calm, with no measurable shift in magnetic declination, dogs pooped with their bodies lined up along the north–south axis, facing either north or south, and tended to avoid east–west. As the field got more restless, the preference faded, and in the most disturbed conditions it vanished. The best predictor wasn’t the strength of the field but how fast its direction was changing.

Calm periods were the minority. The paper’s own figures put them at somewhere between about 18 and 30 percent of cases, depending on which table you read. So even if the effect is real, your dog would show it on a small share of walks, and you have no way of knowing which ones without a magnetometer.

It is a statistical tendency, not a compass needle. In the pooled defecation data, the measure of how tightly directions cluster was about 0.22 on a 0-to-1 scale under calm conditions, and fell to about 0.03 when the field was restless. It looked stronger, about 0.6, when each dog’s observations were averaged first, but that uses only the 43 dogs with enough calm-field poops to count.

Urination was messier. Females showed a weaker north–south lean. Males, who lift a leg, leaned toward a north-west heading instead, and a single borzoi supplied about 44 percent of the calm-field pee records. The authors say plainly that they don’t know the mechanism, or even whether dogs sense the field consciously. Their guess is that dogs may use a stable field to calibrate an internal map, and a shifting field spoils the reading.

Not convincingly. In 2021, Anna Rouviere and Graeme Ruxton (University of St Andrews) published a replication in the Journal of Veterinary Behavior. They measured dogs relieving themselves in five urban dog parks in Lyon, France, and found no detectable magnetic alignment. The dogs did line up non-randomly, but with the layout of each park. The authors suggested that city distractions may override any magnetic preference, and warned that volunteer observers can bias results without meaning to.

Critics of the original paper, including the veterinarian who writes the SkeptVet blog, have argued that grouping the data by field conditions after the fact, and then reporting the subset that showed an effect, raises the odds of a fluke. The authors counter that unstable fields explain why magnetic studies of animals are hard to repeat. Both can be true at once, which is why the honest status is interesting, unconfirmed.

The study did collect one honor: the 2014 Ig Nobel Prize in biology, awarded to research that “first makes people laugh, and then makes them think.”

Whatever the magnetic story, the pre-poop routine has simpler parts. Dogs sniff to read who has been there, pick a spot, and often circle to flatten grass and check their surroundings while they are briefly vulnerable. Some of that circling might involve settling on a direction, but no study has shown your backyard dog is consulting the planet each morning.

What happens after is better studied. That backward kick is a signal to other dogs, not an attempt to bury anything: see why dogs kick after pooping. And if you want another case of a dog’s senses picking up something we can’t, try can dogs smell stress?

If you want to run your own experiment, a phone compass and a notebook will do. Just know that one dog, a few dozen walks and an unknown magnetic forecast won’t settle a question that 70 dogs and two years of data left open.