A DOG’S life might be even more difficult than anyone realised. Scientists have found that canines are prone to a raft of complex, unpleasant emotions such as jealousy, pride and envy.

They hate to see their owners offering affection to other creatures, especially other dogs, and seem to suffer particularly badly when their owners bring home new boyfriends or girlfriends, perhaps fearing they might be displaced.

“We are learning that dogs, horses, and perhaps many other species are far more emotionally complex than we ever realised,” said Dr Paul Morris, a psychologist at the University of Portsmouth who studies animal emotions. “They can suffer simple forms of many emotions we once thought only primates could experience.”

Until recently, psychologists believed most animals lacked the “sense of self” needed to experience so-called secondary emotions such as jealousy, embarrassment, empathy or guilt. These are more complex than feelings associated with instant reaction – such as anger, lust or joy.

The dog study is the latest into several species, including cows, horses, cats and sheep, which have shown that animals are far more self-aware than previously realised.

In the latest, Dr Friederike Range, of the University of Vienna’s neurobiology department, described how dogs feel intense jealously when they spot that they are unfairly treated compared with other dogs.

Range’s results, described at a recent conference, will be published tomorrow. “Dogs show a strong aversion to inequity,” she said.

Morris goes further. In research among dog owners, he found almost all of them reported jealous behaviour by their pets. The dog often tried to prise their owner away from a new lover in the early days of a relationship.

Times Recommends

• The bright side of this winter rain
• Story behind the picture: Snow Leopard, 2008
• Times Charity Appeal: The Place2Be