They Study it in Vienna

But we're living it every day here on the farm:

Dogs can sniff out unfair situations and show a simple emotion similar to envy or jealousy, Austrian researchers reported Monday. Dogs sulked and refused to "shake" paws if other dogs got treats for tricks and they did not, said Friederike Range, an animal psychologist at the University of Vienna, who led the study into canine emotions. "It is a more complex feeling or emotion than what we would normally attribute to animals," said Range.