When Barney put his chocolate-colored nose to work in Howard County's Circuit Court clerk's office, the 2-year-old Labrador mix sniffed out the mold that employees had long suspected was aggravating their allergies.
He also put a new - and furry - face on an issue that has beset homeowners and insurance companies as mold-related claims have soared in recent years.
The concept still evokes giggles and eye rolls, but mold-detecting dogs have slowly gained prominence as concern grows about the adverse effects of the fungus.
Dozens of the canines are at work in the United States - two of them, including Barney, are based in Maryland - and handlers say they are receiving an increasing number of calls for the dogs' service.
Like bomb and drug dogs, the canines rely on an a keen sense of smell, one far more sophisticated than that of humans, to detect mold growths on carpet, on ceilings and behind walls.
"That could be dynamite for all he knows," said David Marcelli, Barney's handler. "He just knows that it's something he was trained on."
Dogs can "discriminate between very chemically similar odors," said Paul Waggoner, the interim director of the Canine and Detection Research Institute at Alabama's Auburn University. Waggoner said he has heard of mold dogs but has not studied them.
"What's remarkable about dogs is their ability to find very weak ... odors amidst a very odor-noisy environment," he said.
A report issued in May by the Institute of Medicine found that mold is an irritant and a factor in respiratory ailments, but it found no conclusive link between mold and other illnesses that have been attributed to mold exposure. The report called the "excessive" indoor moisture that causes mold growths a "public health problem."
Government experts have maintained that despite uncertainty about the health problems that come with exposure to mold, it is best to find the growths and clean them up.
That's where Barney and his ilk come in.
Sophisticated detection equipment and methods often miss large swaths of the fungus, scientists working in the industry say. Workers identify a patch only to take down the wall and find much more, said W. Edward Montz Jr., president of Pottstown, Pa.-based Indoor Air Solutions Inc.
After realizing that he was finding "only the tip of the iceberg," Montz said he happened upon mold dogs in Scandinavia and contacted a local dog trainer in the late 1990s.
Meanwhile, Bill Whitstine, a Florida-based trainer, was focusing on the concept.
"I've got to be honest, as a scientist you've got to show me, and these dogs made a believer out of me," said Montz, an environmental toxicologist.
Although the dogs were producing results, he said, he ran into skepticism among clients who preferred technological detection.
"The dogs are viewed as a kind of sham science or voodoo science ... despite the fact that canines are used for bomb detection," said Montz. He no longer works with the dogs, he said, because the trainer he worked with moved out of state.
Whitstine said that after developing a training method for mold dogs, he put the concept of training bomb dogs on hold after the Sept. 11, 2001, terrorist attacks.
About a year later, he said, an insurance company asked him to show off a dog's skills at a conference in Sacramento, Calif. The concept took off from there.
His Florida Canine Academy near Tampa Bay has trained 50 mold dogs for handlers in the United States and more internationally, he said.
Barney and a second Maryland mold dog, Bear, a black Lab mix, were trained at the academy.
Marcelli and his wife, Rondra, who have a background in mold remediation, have been working with Barney through their Westminster-based company, Mold Trackers LLC, since last summer. The couple charge a flat fee of $275, plus $75 an hour and sampling costs.
Steven P. Yerger, who does water consultation and contracting work out of New Windsor, began working with Bear in April through BCRS K9 Mold Detection. Yerger said his prices range from a few hundred dollars for a partial investigation to between $600 and $800 for a full investigation, plus sampling costs.
Yerger said the two companies will complement each other.
"There's so much work out here right now," said Yerger, who said he does one or two investigations a week.
After a year in the business, the Marcellis said, they are so busy that they might get a second dog.
The Marcellis said they are also working with a developer to inspect construction after walls have gone up but before the insulation can seal moldy materials in.
"It's unique. People laugh at us at the beginning until they figure out what we're about," Rondra Marcelli said.
Howard Circuit Court Clerk Margaret D. Rappaport said she sought out the Marcellis after one of her employees saw their booth at the Howard County Fair. She wants to find out what's been making her workers sick, she said, and correct it before renovations begin in her office next month.
"All they want is a clean, healthy place to work. ... Why put good over bad? That's one of the reasons I wanted to see the mold dog," Rappaport said.