Our agency has 2 WC certified nurses, but since the agency paid for their course and certification, travel expenses to and from, etc.,they don't get paid any more than the regular nurses do.
Most agencies I tihnk do have at least one WC nurse on board.. and when we run into difficult/problematic wounds, we will send that nurse out for a visit to see what else might be done. Other than that, this nurse does the regular visits jsut as we do. Until something pops up again which would require a little more expertise.
Alll agencies are different, but it's worth checking around !