On a sunny winter morning, the dog trainer Mario Fortebraccio slowly bends toward a line of potted olive trees and indicates it with his hand. Waiting for that signal, Paco, a three-year-old white Labrador, rushes through the row of plants with his head tilted, sniffing each pot at the root, the rhythm of his inhaling echoing through the greenhouse. The dog is carefully scouting for something humans can't sense.

"They don't do anything if there is no reward," Fortebraccio tells me with a smile. After a few seconds, having completed his task, Paco returned to the trainer, lifted his leg to urinate on a nearby plant, wagged his tail, and claimed a little crunchy treat.