H5N8 avian influenza has been identified in a dog in Korea. The dog was from a duck farm in the South Gyeongsang province.  While other dogs in the past have been found to have antibodies against the virus, this the first report of finding the antigen in a dog.

It’s an important distinction.

Antibodies mean a dog has been exposed to the virus and mounted an immune response. Antigen means that the actual virus was found, usually at an external surface such as the nose, throat or in feces. It’s not clear where the virus was found (e.g. nasal swabs, feces…) or how it was detected.

It’s suspected that the dog ate an infected bird on the farm. That makes sense, since ingestion of infected birds has been shown to transmit the virus to other species as well. What this means in the bigger picture is unclear.

The dog was clinically normal, which is good for the dog but also raises some public health concerns. If dogs can be infected and shed live virus, then there would be concern that they could be infectious (able to transmit the virus) to other animals or people. It’s a big step from "antigen + clinically normal" to "infectious," and most likely dogs are rare, dead-end hosts (i.e. individuals that can become infected but do not pass on the virus). Care must be taken not to over-react, but it means that the potential role of dogs in virus transmission needs to be studied.

I haven’t seen any information about what happened to the dog. Hopefully it was just isolated and monitored, since only short-term influenza shedding would be expected.