A dog’s sense of smell is one of the most powerful in the animal kingdom. With up to 300 million olfactory receptors(compared to about 5 million in humans), dogs are biological marvels when it comes to scent detection. When a mold dog is trained to recognize MVOCs, it can detect mold growth behind drywall, under flooring, or even in ductwork—all without the need for invasive testing.

However, this same sensitivity comes with challenges. Dogs may pick up on tiny, non-threatening traces of mold spores from outdoor air that slipped through a window or door. This can result in alerts where no active mold problem exists. These alerts aren’t “wrong”—they just highlight how incredibly fine-tuned a dog’s nose is. It’s part of why results should always be interpreted carefully and followed up with further inspection or testing if needed.

Despite occasional false positives or the rare missed detection (such as in the case of long-dead mold that no longer emits scent), mold dogs remain one of the fastest, most non-invasive tools available to identify mold problems early. Their contributions to indoor air quality assessments are especially valuable in homes with sensitive occupants or unexplained health symptoms.