To amend that, the best way to put what it means is that in the US, dogs are not a reservoir for rabies. They can catch it, and they can pass it on, but dogs, as a group, are no longer a source of rabies in this country, the way they still are in, say, India.
It also means that wide-spread vaccination has worked. Not that we can stop doing rabies vaccination (just recently a raccoon torn up a border collie around here . . . we don't know if it was rabid, but everyone was glad that dog was vaccinated). But we have taken a disease endemic to dogs, so much so that it was sometimes called 'dog-madness', and wiped out its natural occurance from those hosts. Its a reason to cheer.