Can dogs carry the global pandemic candidate avian influenza virus H9N2?

Background H9N2 avian influenza virus (AIV) is one of the most widely circulating viruses in Eurasia. Recent studies have shown that the molecular recombination of H9N2 and H1N1 could pose a pandemic threat. Mammals that are susceptible to subtype H9N2 may contribute to the spread of the virus. Objective To determine the susceptibility of 1-year-old dogs to H9N2 AIV. Procedure H9N2 AIV infection was experimentally reproduced in 1-year-old dogs. The animals were intranasally inoculated with a titre of 107.5 (50% egg infective dose) of H9N2 AIV isolated from a broiler farm during an outbreak. The animals in the contact group were exposed to contaminated surfaces. Results Clinical signs including sneezing, coughing and nasal discharge were observed in the inoculated and contact groups. The virus was detected in nasal swab, faecal and buffy coat samples of dogs in both the inoculated and contact groups and both groups developed antibody titres against AIV H9N2 subtype. Conclusion H9N2 AIV isolated from outbreaks in a broiler farm can easily infect dogs and infected animals shed the virus. Because many Asian countries are facing frequent outbreaks of H9N2 infection in the poultry industry, dogs could be a potentially important source of virus transmission within and between poultry farms.