Rudy is the nose behind Mold Dog of Virginia, based in Norfolk. “We’re constantly training so his nose stays calibrated to mold,” said Lacey Lee, Rudy’s owner and Mold Dog of Virginia founder.

As many mold dog proponents say, "the nose knows." Compared to other methods of testing for mold, mold-sniffing dogs do a more thorough sweep than equipment alone. This equipment often relies on ...