A study has shown a bird flu strain that has killed dogs can spread from one dog to another, showing that the disease is capable of crossing species and causing sickness in mammals.

Dozens of dogs in South Korea have been sickened by the H3N2 strain of the bird flu virus, stated researchers in Emerging Infectious Diseases journal. The virus taken from the infected dogs were analysed to see if pathogens were capable of spreading from dog to dog.

According to Bloomberg, these findings add to scientific understanding of how flu viruses evolve in animals and the risks they pose to humans.

Many scientists and researchers in the field fear that the highly pathogenic H5N1 bird flu virus could spread, like the H3N2 virus in this study.

"Transmission of avian influenza A virus to a new mammalian species is of great concern because it potentially allows the virus to adapt to a new mammalian host, cross new species barriers, and acquire pandemic potential," the Korean researchers* said.

The N3N2 virus found in the dogs closely resembled those found in chickens and doves in South Korea in 2003. It is believed that the pathogens may have been transmitted from birds to dogs fed raw, minced meat from infected ducks and chickens.

Dogs may be more susceptible to flu strains carried by birds because both canines and birds share a type of virus-binding site in their respiratory systems that is less common in humans. Also, it is said that the H3N2 virus was excreted in nasal discharges and caused sneezing of experimentally infected beagle puppies, the study found. The virus wasn't active in their faeces.

* This study was led by Daesub Song, Bokyu Kang and Chulseung Lee of the Green Cross Veterinary Products Co. and Daewoong Pharmaceutical Co. at Yong-in.