Researchers at Canisius College found that the relationship between two dogs living in the same household may impact how much influence they have on each other's behavior. Dogs who showed little to no aggression towards their housemates were more likely to automatically follow each other than dogs who viewed their canine housemates as rivals. The study results are reported in the latest issue of Animal Cognition.

To conduct this study, Christy Hoffman, Ph.D., and Malini Suchak, Ph.D., assistant professors of Animal Behavior, Ecology, and Conservation, traveled to 37 multi-dog households to test the dogs in their own homes. This was an unusual approach, since most studies test dogs in the laboratory and often pair them with other dogs they don't know. "We really wanted to look at the impact of the relationship between the dogs on their behavior, and doing that in a setting natural to the dogs, with dogs they already know, is really important," Suchak says.

To classify how competitive household dogs were with each other, the owners were asked to fill out a survey known as the Canine Behavioral Assessment and Research Questionnaire (C-BARQ). Dogs that were low in rivalry never or rarely displayed aggressive behavior toward the other dog. Dogs that were high in rivalry displayed some degree of aggression around valuable resources, suggesting they have a more competitive nature. After their owners completed the C-BARQ, the dogs participated in a simple task. A research assistant placed two plates containing food in front of both dogs. One dog was allowed to approach the plates and eat the food from one plate before being walked out of the room. At that point, the second dog was allowed to make a choice. If the second dog followed the first dog, he arrived at an empty plate. If he didn't follow the first dog, he went straight to the plate that still contained food.

Dogs that were low in rivalry were more likely to follow the first dog and frequently ended up at the empty plate. What surprised the researchers was that low rivalry dogs only blindly followed the demonstrator when allowed to make their choice immediately. "Low and high rivalry dogs only differed in the choices they made when there was no delay," Hoffman says. "When they had to wait 5 seconds before making their choice, all dogs tended to go directly to the full plate."

Suchak adds, "This suggests that the low rivalry dogs may have been automatically following their housemates. When we forced the dogs to wait, it was as if the low rivalry dogs actually took the time to think about the situation, and they went straight for the food."

The researchers also tested the dogs in a condition where a human removed the food from one plate before the dog made a choice. Interestingly, low rivalry dogs were more likely to follow the human demonstrator when there was no delay, a finding that paralleled what happened with dog demonstrators. Hoffman suggests this may have to do with the personality of low rivalry dogs, "Since the tendency of the low rivalry dogs to follow was seen when the demonstrator was both another dog and a human, competitiveness may be a characteristic of the individual that extends beyond their relationship with other dogs."

This means that if owners have a high rivalry dog "that dog may be more likely to think for himself, and less likely to blindly follow, than a dog that is less competitive," says Hoffman. "On the whole, our findings show there is variation in the ways dogs make decisions and that how dogs interact with others plays a big role in how they respond under conditions that require quick thinking."