Dogs, Jealousy, And Welfare
Dog-dog and dog-human aggression affect millions of animals worldwide; they are issues both in shelters and on the streets. Previous research has shown that, as in primates, dogs show sensitivity to “reward inequity” – they react negatively when other dogs receive a greater reward than they do. As one of the prerequisites for aggressive behavior, emotions akin to jealousy in humans may trigger attacks. In this study, a group of researchers from the U.S. studied 13 dogs using non-invasive methods. Their goal was to determine if the dogs showed significant changes in brain activity – associated with jealousy in humans – when food was given to another dog.
The basis for this study was the fact that in cases where behavioral responses may be affected by a wide range of uncontrolled factors, neural responses can serve as a reliable indicator of behavioral inclinations. In a similar way, people often look at an individual’s behavioral tendencies over time, defined as temperament. When assessing it, caregivers typically rate their dog’s behavior on a number of scales. These yield measures of the dog’s likelihood for attachment behaviors, aggression, anxiety, and a wide range of other factors.
Previous work of the same research group had, in fact, already shown that a dog’s temperament can be used predictively for neurobiological responses to prosocial stimuli. This study expanded on the idea further by testing the approach and assessing potentially anti-social reactions to threats to resources, as in treats given to other dogs. They predicted greater amygdala (brain area involved in aggression among other emotional states) activation when dogs watched their caregivers give a food reward to a fake dog than when they put the food in a socially irrelevant object (a bucket). Furthermore, dogs with more aggressive temperaments were predicted to show even more amygdala activation. A fake dog was used as the “other dog,” as it’s easier to manage one dog and a dog sculpture than two dogs simultaneously.
When observed in humans, jealousy manifests as negative emotional and behavioral responses when rivals receive something one wants for oneself. The researchers argue that it is indeed a complex emotion, sharing brain activities with anger and sadness. What they found was that, indeed, dogs exhibit reactions that could be seen as evidence of proto-jealousy. They also found that such brain responses could be great predictors of future behavior.
In another previous study by the same group, dogs who exhibited greater activity when expecting verbal praise than while expecting food, were also more likely to prefer interacting with their caregiver over eating treats. As predicted, they found that dogs of a higher aggression temperament not only showed higher amygdala activation to the fake dog, but also exhibited a greater level of habituation. This suggests that behavioral interventions involving controlled exposure to interactions between their caregivers and other dogs, could be an effective therapy for dogs who show jealous aggression.
Be it driven by jealousy or reward inequity, the observed amygdala responses were very different when food was deposited into a bucket, suggesting that the aggressive subjects were socially sensitive. Dogs became agitated because the ‘other dog’ received attention and food, while simply not receiving a potential treat was met without much arousal. With many incident reports quoting dog aggression victims being attacked “without prior warning”, studying and interpreting covert aggression may prove to be vital for dog guardians and rest of society. Who knows, it might be possible to correlate amygdala activation with changes in canine facial expressions, for example, in the future.