Paw and hand preferences are of great interest in behavior and psychology because they are an indication that one side of the brain is more active than another. A preference for using the right side of the body (hand or paw) is associated with a more active left side of the brain while a preference for using the left side of the body indicates more activity in the right side of the brain. (Each side of the body is controlled by the opposite side of the brain.)
The relative activity of one hemisphere of the brain compare to the other matters because the two hemispheres of the brain have different functions related to emotional processing. The exact distribution of brain function across the two sides is still being explored. In general, the left hemisphere is more heavily engaged in processing positive emotions such as happiness, excitement and affection as well as anything familiar while the right hemisphere is more active in dealing with novel things and negative emotions like fear and sadness. Since many behavioral issues are a result of fear, anxiety and various types of emotional reactivity, an animal’s emotional tendencies are likely to influence their propensity to develop certain behavioral issues. Since paw preference is associated with emotional tendencies, it is unsurprising that some behavior problems have been linked with paw preference patterns.
There is a large body of research on lateralization of brain function, which is often studied indirectly via paw and hand preferences. Previous research in dogs has shown differences such as a greater frequency of stranger-directed aggression in left-pawed dogs than in right-pawed or ambilateral dogs and also that being right-pawed was associated with being more calm and exhibiting lower arousal in response to strangers and new things. Ambilateral dogs have been documented to be more reactive to loud noises than dogs with a paw preference. Interestingly, humans who are ambidextrous are more prone to develop PTSD than people who favor one hand over the other.
A recent study called “Lack of association between paw preference and behavior problems in the domestic dog, Canis familiaris” explored possible associations between paw preference and behavioral problems. Dogs with and without behavior problems were recruited to participate in the study. Of these, 52 dogs had behavior problems and 61 did not. Each dog was tested with a stuffed Kong to determine their paw preference. Every time a dog used a particular paw to stabilize the Kong, that preference used was recorded until the dog had stabilized the Kong 100 times. An overall preference score is then calculated that ranges from +1 for strongly left-pawed dogs to -1 for completely right-pawed dogs. If the results suggested a high likelihood that the distribution of paw use by a dog was not different than that expected by chance, the dog was considered ambilateral.
To assess their behavior, each the guardian of each dog in the study filled out 100 questions of the C-BARQ (Canine Behavioral Assessment & Research Questionnaire). The C-BARQ is a commonly used tool designed to provide researchers with evaluations of canine behavior and temperaments in a standardized way.
Of the dogs in the study, 47 percent were ambilateral, 25 percent were left-pawed and 28 percent were right pawed. There were no differences between the two groups of dogs (those with and without behavior problems) in terms of distribution of paw preference or the strength of those paw preferences. The dogs with behavior problems did score higher on the C-BARQ in 7 of 14 categories of behavior issues—stranger-directed aggression, stranger-directed fear, dog-directed aggression, dog-directed fear, non-social fear, touch sensitivity, and trainability. The group without behavior problems scored higher on aggression towards familiar dogs than the dogs with behavior problems. There were no differences between the two groups of dogs in their scores on separation-related problems, excitability, attention-seeking, chasing, owner-directed aggression and energy.
This study found no significant difference in the distribution of paw preference in the two groups of dogs. The relatively small sample size would make it hard to find such a difference, especially as the behavior problem group was made up of dogs with a variety of issues. Future studies in which all of the behavior problem dogs have the same issue might be more likely to reveal a pattern.
Despite the phrase “lack of association” in the title, the study actually did find some associations of paw preference with behavior problems. Dogs who were left-pawed had lower scores (indicating less issues with) stranger-directed aggression than dogs who were right-pawed or ambilateral. Additionally, the results showed that the stronger the right paw preference of dogs in the behavior problem group were, the higher their scores were on three behavioral issues—stranger-directed aggression, stranger-directed fear and attention seeking.
These results are not entirely consistent with previous research on lateralization which would have predicted that left-pawed dogs, especially those with a strong preference, would be more likely to have these issues. The authors have suggested that perhaps the paw preference test they used is inaccurate. Perhaps the paw used to support the body is the preferred paw rather than the one used to stabilize the Kong. If that is the case, then their findings would line up with previous work that assessed paw preference differently. (Many studies do use the Kong test, however.) Another consideration is that recent research has suggested that although paw preferences are stable over time, they may vary across different tasks. A comparison in humans would be if we tended to make different choices about which hand to use depending on whether we were using a fork, writing or throwing a ball.
This study did more to muddy the waters about lateralization and behavior problems than to enlighten us about the connections. When the goal is trying to uncover the truth about things as complex as our dogs’ brains and their behavior, it’s no surprise that progress is not smooth or straightforward. Though that can be frustrating, it’s also a good reminder that this is how science moves forward much like a young puppy—in uneven steps and not always in the same direction.