Dogs know that we don’t give them equal opportunities. Study conducted in the year 2008 and published in Proceedings of the National Academy of Science proved that dogs that saw that other dogs were given treats for doing a trick, for which they didn’t get anything themselves, were agitated, scratched themselves and avoided eye contact. It happened more often that in the situation in which they were alone and didn’t get the treat. Dog jealousy, however, is not as sophisticated as the human one. Animals didn’t seem to care about the fact that other dogs received a sausage whereas they got only bread. They also weren’t bothered by the fact that they had to do a trick in order to get a treat, while others got it having done nothing. However, according to scientists, these discoveries prove that being green with envy is not only the feature of primates.

Source: www.livescience.com