Dogs catch influenza virus directly from birds

Dogs may have a role in interspecies transmission and spread of influenza virus as they catch the flu directly from birds. Doctors know animals pass flu viruses to one another. Many experts believe that most, if not all, influenza viruses originate from birds. The H5N1 avian influenza virus, which is sweeping through flocks in Asia, Africa and parts of Europe, has occasionally passed to humans, infecting 376 people and killing 238 of them. It has also occasionally infected dogs, cats, clouded leopards, civets and dozens of bird species, from swans to coots. The fear is that it will somehow change or combine into a form that is easily passed from one human to another, triggering a pandemic that could have the potential to kill hundreds of millions of people globally. H3N2 is found in birds and is also a very common human flu strain. But the varieties that infect birds and people look different on the genetic level. Korean researchers investigated outbreaks among dogs last year from May–September, and found that cases of severe respiratory disease had occurred in animals at three veterinary clinics located 10 to 30 km (6–8 miles) apart in Kyunggi Province and one kennel located in Jeolla Province (southern South Korea). A miniature schnauzer recovered, but a cocker spaniel, two Korean Jindo dogs and a Yorkshire terrier died. Another 13 dogs in a shelter were affected, and there is evidence some dogs infected others. DNA analysis showed the viruses from the dogs closely resembled those from Chinese chickens or ducks in Hong Kong, Japan and China. This infection could have transmitted to the dogs through the food they were fed: untreated minced meats of ducks or chickens. In South Korea, untreated duck and chicken meats, including internal organs and heads, are widely used to feed dogs for fattening in local canine farms or kennels. It is possible that some of the dogs were infected via respiratory secretions in live bird markets, and passed the virus to others. Live-bird markets are thought to constitute a missing link in the epidemiology of avian influenza viruses because they bring together numerous hosts, such as chickens, ducks, turkeys, geese and doves, in a high-density setting, which represents an ideal environment for virus interspecies transmission. This is a cause of great concern because it potentially allows the virus to adapt to a new mammalian host, cross new species barriers and acquire pandemic potential.