Figure. Phylogenetic trees of influenza subtype H3N8 viruses showing analyses conducted on A) hemagglutinin genes, B) neuraminidase genes, and C) matrix genes. Sequences from dogs are from the same animal on successive days. Boldface indicates viruses identified in dogs and horses in Australia, 2007, asterisks (*) indicate viruses from horses in Japan, and daggers (†) indicate viruses from dogs in the United States. Bootstrap values >50 are indicated at branch nodes. Bootstrap trials = 1,000; seed = 111.