How to Tell if Your Dog is Left-Handed or Right-Handed, According to Science

“The hand” – a tendency to prefer one hand over the other – is almost universal among humans. The majority of people, approximately about 90 percentare considered right-handed, with most others favoring their left hand, and a small group may truly use the two interchangeably. It’s not just us: other animalsincluding some monkeys, rodents and reptiles, also seem to have their own version of “manity.” In dogsit’s called “paw” – and if you’re a pet owner, it’s something you can try with your dog at home.

In a new study published Wednesday in Royal Society Open Scienceresearchers from the University of Bari Aldo Moro in Italy describe a paw test in dogs. The test classifies animals into categories including “strong left paw,” “weak left paw,” “ambilateral,” “weak right paw,” or “strong right paw.” Researchers call it the “Doginburgh Inventory,” after a similar test in humans called the Edinburgh Hand Inventory.

It’s a useful tool because it can help researchers understand how brain lateralization (the use of one side or the other of the brain for certain tasks or functions) “is linked to behavior, emotion and cognition, not only in dogs but also in other species,” says Shany Drora postdoctoral researcher at the Clever Dog Lab at the University of Veterinary Medicine Vienna, who was not involved in 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 “handling” tests and two “locomotion”-based tests. All are easy to reproduce at home, says study co-author Marcello Siniscalchi, professor of veterinary physiology at the University of Bari Aldo Moro.

In one test, dogs were given a Kong toy (essentially 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, researchers tracked which paw the dogs used to search for a treat under a piece of furniture, like a couch or bed.

In a third test, the researchers measured which paw the dogs preferred when they went from sitting at the top of certain stairs to walking down the steps. And in another test, researchers tracked which paws the dogs preferred when they stepped off a single ledge during a leash walk.

To replicate these tests at home, owners should 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 that can skew your results, he adds.

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

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

If “R” is the 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 this decimal by 100. You should now have a number between -100 and 100. This gives you an idea of which category your dog falls into 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 these categories must correspond to a value of –2, –1, 0, +1 or +2. This is your dog’s paw score on each test.

Combining your dog’s score on all four tests is trickier. To determine your dog’s overall paw, add the total positive scores (R) and the total negative scores (L) separately, then repeat the same equation: (R – L) / (R + L). For example, in one 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 walk test. This dog’s equation would be: (4 – 1) / (4 + 1). Again, multiply the resulting decimal by 100.

To account for a dog’s consistency from test to test, the researchers also divided the total number of tests in which dogs showed a paw preference by the total number of tests. So if, say, your dog showed a preference for his right or left paw in three out of four tests, you would get 0.75.

The final step in the process is to multiply this consistency score by the number of legs for all tests. In the same example as above, it would be: [(4 – 1) / (4 + 1) × 100] × 0.75 = 45. The dog is “weak, straight paw”.

There you have it: your dog’s overall paw score.

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

Siniscalchi hopes other scientists will adopt the scoring system to help standardize and speed up paw research in dogs. “It’s a small starting point,” he said.

Pet owners can also help. “We want to have a very, very large data set” on paw preferences, “like in humans,” Siniscalchi says. If the measurement becomes “widespread” among animal caregivers around the world, “we will be able to have more data to study this phenomenon,” he says.