Dogs showing separation-related behavior exhibit a 'pessimistic mood'

"We know that people's emotional states affect their judgments; happy people are more likely to judge an ambiguous situation positively," said Mike Mendl of the University of Bristol. "Now it seems that this may also apply to dogs; dogs that behaved anxiously when left alone also tended to judge ambiguous events negatively. Their anxious behavior may reflect an underlying negative emotional state."

The new findings also raise the possibility that some dogs may be more prone to responding anxiously when left alone than others, and that this is related to their general mood. That's important because "separation-related behavior is common in dogs, so predicting which dogs may develop this, and treating them appropriately, is very important for ensuring good dog welfare," Mendl said.

The researchers conducted the study with 24 dogs, both male and female, that had recently entered into one of two animal re-homing centers (shelters) in the United Kingdom. Each dog was first tested for separation anxiety-related behaviors. A researcher interacted with each dog in an isolated room for 20 minutes. The following day, they took the dog back to the room and then left it alone for a period of five minutes while its behavior was captured on video. In those five minutes, the researchers observed barking, jumping on furniture, scratching at the door, and repetitive behaviors to varying extents depending on the dog.

In order to study decision making in those same dogs, the researchers trained them to expect that when a bowl was placed at one location in a room (the "positive" position), it would contain food, but when placed at another location (the "negative" position), it would be empty. They then placed the bowl in ambiguous locations in between the positive and negative positions. Dogs that ran quickly to those ambiguous locations, as if expecting the positive food reward, were classed as making relatively "optimistic" decisions. Dogs that didn't approach the bowl as if they were expecting a food reward were judged to be "pessimistic."

An analysis of the two sets of behavioral data found that dogs that made more "pessimistic" judgments about whether they would find a food bowl empty or full also expressed more separation-related behaviors.

The results suggest that behavior regarded as "problematic" for owners also has emotional significance for the animals concerned, even when the behavior itself isn't being expressed, the researchers conclude. Mendl says the results also suggest that "optimistic" versus "pessimistic" decision making may be a valuable new indicator of animal emotion.

Dog owners should take note. "Some owners think that dogs showing anxious behaviors in response to separation are fine and do not seek treatment for their pets," Mendl says, noting that he and his colleagues have validated treatments for dealing with these types of behaviors in past work. "This study suggests that at least some dogs showing separation-related behaviors may have underlying negative emotional states, and owners are encouraged to seek treatment to enhance the welfare of their dogs."