How to tell if your dog is left-pawed or right-pawed, according to science

“Handedness”—a tendency to prefer one hand over the other—is almost universal to humans. The majority of people, approximately 90 percent or so, are thought to be right-handed, with much of the rest favoring their left hand, and a tiny group can truly use both interchangeably. It’s not just us: other animals, including some apes, rodents, and reptiles, appear to have their own version of “handedness,” too. In dogs, this is called “pawedness”—and if you’re a pet owner, it is something you can test with your dog at home.

In a new study published Wednesday in Royal Society Open Science, researchers at the University of Bari Aldo Moro in Italy describe a test for pawedness in dogs. The test sorts the animals into categories, including “strong left-pawed,” “weak left-pawed,” “ambilateral,” “weak right-pawed” or “strong right-pawed.” The researchers call it the “Doginburgh Inventory,” after a similar test in humans called the Edinburgh Handedness Inventory.

It’s a useful tool because it can help researchers understand how brain lateralization—using one side of the brain or the other for certain tasks or functions—“relates to behavior, emotions, and cognition, not only in dogs but also in other species,” says Shany Dror, a postdoctoral researcher at the Clever Dog Lab at the University of Veterinary Medicine, Vienna, who was not involved with the new study. In humans, the right side of our brain guides our left hand, while the left side controls the right hand. The same is true in dogs.

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In the new study, researchers evaluated dozens of dogs across four tests: two “manipulation” tests and two “locomotion”-based tests. All of them are easy to replicate at home, says study co-author Marcello Siniscalchi, a professor of veterinary physiology at the University of Bari Aldo Moro.

In one test, the dogs were given a Kong toy (basically a rubber cone with rounded edges) with treats inside. The team recorded which paw the dogs used to stabilize the toy while searching for treats and repeated the test several times. Similarly, in another test, the researchers tracked which paw the dogs used to reach for a treat under furniture, such as a couch or bed.

In a third test, the researchers measured which paw the dogs preferred when going from sitting at the top of some stairs to traveling down the steps. And in another test, the researchers tracked which paw dogs preferred when they stepped down a single ledge during a leashed walk.

To replicate these tests at home, owners need to try not to influence a dog’s movements in any way, Siniscalchi says. You can also repeat the leash test by walking on both sides of your dog to see if the results are consistent.

“It’s easy to do, but be careful,” he says. Pay attention to details which may skew your results, he adds.

After completing the four tests, the researchers performed a series of calculations to give the dogs their overall pawedness score. Owners can also do a similar process at home:

Tally the number of times your dog used their right paw or left paw for each separate task. Then, use this equation:

If “R” is number of times their right paw was used in a task and “L” is the number of times they used their left for each task, then you can calculate: (R – L) / (R + L).

For each task, you should get a decimal value between –1 and 1.

Multiply that decimal by 100. You should now have a number between -100 and 100. That gives you a clue as to which of five categories your dog belongs to for each test: “absolutely left” (–100 to –60), “left” (–60 to –20), neutral (–20 to 20), “right” (20 to 60) or “absolutely right” (60 to 100), according to the study. Each of those categories should correspond to a value of –2, –1, 0, +1 or +2. That’s your dog’s pawedness score on each of the tests.

Combining your dog’s score across all four tests is trickier. To determine your dog’s overall pawedness, add up the total positive scores (R) and the total negative scores (L) separately and then repeat the same equation: (R – L) / (R + L). For instance, in a scenario used in the study, a hypothetical dog scores –1 on the Kong test, +2 on the treat reach test, +2 on the stairs and 0 on the walking step test. That dog’s equation would be: (4 – 1) / (4 + 1). Again, multiply the resulting decimal by 100.

To account for a dog’s consistency across tests, the researchers also divided the total number of tests where the dogs showed a paw preference by the total number of tests. So if, say, your dog showed a preference for either its right or left paw in three out of four tests, you’d get 0.75.

The last step in the process is multiplying that consistency score by the pawedness number for all tests. In the same example as above, that’d be: [(4 – 1) / (4 + 1) × 100] × 0.75 = 45. The dog is “weak right-pawed.”

And there you have it: your dog’s overall pawedness score.

In the study, some dogs showed a clear left or right preference, but there was no overall trend for pawedness across all the dogs. And, as Dror notes, many of the dogs used different paws for different purposes. “It’s interesting to see that, according to the current study, in different situations, dogs may exhibit a different extent of paw preference,” she says. More research is needed to better understand why.

Siniscalchi hopes other scientists will adopt the scoring system to help standardize and accelerate research on pawedness in dogs. “This is a small starting point,” he says.

Pet owners can help, too. “We want to have a very, very huge dataset” of paw preference, “like in humans,” Siniscalchi says. If the measurement becomes “widespread” among animal caregivers all over the world, “we can have more data to study this phenomenon,” he says.