The virus was also found in a similar bird found alive but unable to fly in Wexford Town on December 28.
The Department of Agriculture, Food and the Marine said in a statement that the latest case confirms poultry flocks across the country are at risk from the virus.
Although the H5N8 virus subtype can cause serious disease in poultry and other birds, no human infections have been reported world-wide. While the risk to humans is considered very low, the public is advised not to handle sick or dead birds.
Department staff will continue to collect sufficient birds for testing to help understand how the disease is distributed geographically, in different species and over time.
It is being assisted in this task by patrols carried out by rangers from the National Parks and Wildlife Service.
Confirmation of the second case in Galway, has led to renewed calls on poultry owners to remain vigilant for any signs of disease in their flocks. The strain was previously found in Britain and mainland Europe.
The department has again reiterated the requirement to confine poultry and other birds, and to apply strict bio-security measures. It said these steps are necessary to prevent the introduction of avian influenza into poultry and captive bird flocks.
Agriculture Minister Michael Creed had earlier introduced regulations requiring the compulsory housing of poultry as a result of the increased threat.
Irish Farmers Association Poultry Committee chairman Nigel Renaghan welcomed the decision to issue a housing order requiring all poultry and captive birds to be kept within a secure building. He urged all flock owners to review their bio-security protocols.
Meanwhile, flock owners have been asked to report any disease suspicion to their nearest Department Veterinary Office.
All birds at Dublin Zoo have also been moved indoors as a precautionary measure.