The virus is said to have begun as a form of bird flu - known as the H3N2 strain - which has already evolved and is affecting dogs.

But scientists have raised concerns that the strain is mutating again, and could soon be strong enough to infect humans.

The strain H3N2 first infected dogs in 2006, with the strain originally descending from bird flu.

Scientists warned there was a concern that if bird flu evolved to be able to affect mammals - such as dogs - there was a chance it could mutate to be stronger and then be able to be transmitted to humans.

Scientists have warned the variant has now evolved to become a mammalian-adapted form of avian influenza.

Studies featuring 4,000 dogs at the China Agricultural University have looked into the dangers of the form spreading.

The bird flu specialists found that the virus was “better able” to “recognise human cell receptors and replicate in human cells.”

The findings were published in science journal eLife, and stated: “Our results showed that canines may serve as intermediates for the adaptation of avian influenza viruses to humans.”

Six dogs were intentionally infected with the known dog flu strains of H3N2 but it was found that each was “merely mildly unwell”, with symptoms for the illness including a fever, sneezing and coughing.

Professor James Wood, the head of the department of veterinary medicine at the University of Cambridge told The Independent: “The changes in the canine virus apparently are making it better adapted to transmit within mammals, as you might expect after such a long period in dogs.”