Dogfighting and the Feds

Recently Michael Vick's home was searched by federal agents suspicious that he was part of an illegal dog-fighting ring. I seriously don't know what to make of this--I'm trying to understand what the federal government's motive is in getting involved in this case--surely there are much more important things that these agents could be spending their time on--following up leads on potential terrorist plots, researching potential white-collar crimes. Will we next hear that FBI agents are going after the subversive cock-fighting ring?