It was previously believed that canines are devoid of 'sense of self' needed to experience so-called secondary emotions such as jealousy, embarrassment, empathy or guilt, however, a new study has shown that dogs are prone to such complex emotions.
Dr Friederike Range, of the University of Vienna's neurobiology department, has shown that dogs feel intense jealously when they spot that they are unfairly treated compared with other dogs.
"Dogs show a strong aversion to inequity," the Telegraph quoted her as saying.
During the study, almost all of the dog owners revealed that their pets of showed jealous behaviour. The dog often tried to prise their owner away from a new lover in the early days of a relationship.
"We are learning that dogs, horses, and perhaps many other species are far more emotionally complex than we ever realised," Dr Paul Morris, a psychologist at the University of Portsmouth who studies animal emotions, told The Sunday Times.
"They can suffer simple forms of many emotions we once thought only primates could experience," he added.
Experts recommend owners keeping their dog's routine as much as possible when a new partner or child comes along in order to prevent jealous activity from the dog such as interruptions with barking or whining.