We are examining the evolution of each of the viruses in order to compare the variation of the viruses as they spread in their different hosts, so that we can see if there is host specific adaptation or other variation in the virus. The studies to date indicate that although the parvoviral DNA sequences are not very variable, mutations frequently arise in both the endemic and epidemic situations. Similarly, the H3N8 and H3N2 CIVs both show steady rates of evolution that is similar to that seen among other influenza viruses, such as those in humans. We are analyzing the processes of viral variation and using the data to understand how viruses can transfer from one host to another.