Dogs are less intelligent than most people think, a new study has found, revealing that canines are no smarter than pigeons, sheep or goats.

Researchers from the University of Exeter reviewed more than 300 papers on animal brain power, comparing dogs with other domestic animals, social hunters and carnivores such as wolves, bears, lions and hyenas.

They found that dogs were at least matched by several species in each of these groups when it came to cognitive ability.

For example, dogs are unable to recognise themselves in a mirror, unlike animals including chimpanzees and dolphins.

Professor Stephen Lea, of the University of Exeter, said the research identified several cases of "over interpretation" in favour of the abilities of dogs in studies.

"During our work it seemed to us that many studies in dog cognition research set out to 'prove' how clever dogs are," Prof Lea said.

"They are often compared to chimpanzees and whenever dogs 'win', this gets added to their reputation as something exceptional.

"Yet in each and every case we found other valid comparison species that do at least as well as dogs do in those tasks."