Pets were twice as likely to nudge an owner playing with a rival dog as when he was looking at a bucket of sweets.

The study in the journal Plos One, is the first experimental test of jealous behaviour in dogs.

Psychology professor Christine Harris, of the University of California, San Diego, said: “Our results show that animals besides ourselves display strong distress whenever a rival usurps a loved one’s affection.”

Researchers, working with 36 dogs, filmed owners ignoring them in favour of a stuffed dog which could bark and wag its tail, a bucket of sweets or reading a book.

Seventy-eight per cent of dogs pushed at the owner when he played with the stuffed dog, but 42% objected to the sweets. Only 22% were bothered by reading the book.