Findings from the Largest Study on Left-Handedness in Dogs

About 10.6% of humans are left-handed (Papadatou-Pastou et al., 2020). While scientific research has shown that many animal species also show left- or right-handedness, the exact numbers are often not known due to small study sample sizes. A new study, published in the journal Applied Animal Behaviour Science, was aimed at determining how many dogs are left-handed and how many dogs are right-handed (Laverack et al., 2021)

What did the researchers do?

The research team, led by first author Kirsty Laverack and corresponding author Elisa Frasnelli of Lincoln University in the UK, analyzed data collected in the BBC’s ‘Test Your Pet’ survey. Overall, an impressive number of 17,901 dogs were tested in this survey. This makes the study by Laverack et al. (2021) the world’s biggest study on left-handedness in dogs.

To determine whether a dog was left-handed (or rather left-pawed) or right-handed, the researchers analyzed data from a so-called food retrieval task. In this task, owners were asked to obtain a plastic or cardboard tube that was wide enough so their dog could reach its paw into the tube. The owners were then instructed to place a treat near the end of the tube, so the dog had to reach into the tube with its paw to reach the treat. In total, this procedure was done three times. While most researchers would conduct more test trials than just three in a laboratory experiment, this low number might be due to the fact that also several other tests were performed in this survey.

The owners then were asked to characterize their dogs’ behavior in this task by choosing one of these three options:

1. The dog uses their left forepaw most of the time.
2. The dog uses their right forepaw most of the time.
3. It is difficult to tell.

Moreover, the gender of the dogs was noted and each dog was classified into one of four age groups—puppy, young adult, adult, and elderly.

What did the researchers find out?

Overall, about 74% out of the 17,901 tested dogs showed a clear paw preference, while the remaining 26% were classified by their owners as using both paws equally in the food retrieval task. Of the dogs that showed a clear preference for one paw over the other, 58.3% were right-handed. This number reached statistical significance, showing that most dogs are right-handed. It is interesting to note that 41.7% of the dogs that showed a paw preference were left-handed. Thus, left-handedness is much more common in dogs than in humans.

Interestingly, gender also affects handedness in dogs. Of female dogs, 60.7% were right-handed and 39.3% left-handed. In male dogs, left-handedness was more common: 56.1% were right-handed and 43.9% left-handed. This mirrors findings in humans that also show that men are more likely to be left-handed. (Learn more here.) Moreover, the researchers found that age affected handedness in dogs: Right-handedness was more common in older dogs than younger dogs, but this effect was specific for male dogs.

What can we learn from this study?

Taken together, the study clearly shows that most dogs are either left-handed or right-handed, just like humans. However, at 24% the percentage of animals with no preference is higher than the percentage of ambidextrous humans which is roughly 1%. Another interesting finding was that in dogs, left-handedness is much more common than in humans. Why this happens is not well understood. One factor might be that humans face stronger cultural pressure to use the right hand; for example when learning how to write in school. In contrast, owners generally do not seem to care much whether their dog is left- or right-handed and would only very rarely try to train it to use the other paw for retrieving food. The effect of gender on left-handedness in dogs suggests that sex hormones may affect handedness in dogs, similar to what has been proposed in humans.