The long-standing image of a domestic pig rooting through the forest floor is deeply connected to the search for one of the world’s most luxurious ingredients. Pigs possess an exceptional sense of smell, making them highly effective partners in locating hidden treasures beneath the soil. This natural ability has made them historically famous for finding a specific category of fungi that is both rare and highly valued in global cuisine. These foraging animals have a strong instinct to uncover food buried deep underground.
The Primary Target: Subterranean Truffles
The fungi pigs are most renowned for finding are truffles, the underground fruiting bodies of the Tuber genus. Unlike common mushrooms that grow above the surface, these species develop entirely beneath the soil, often up to a foot deep. Truffles grow in a symbiotic relationship with the roots of certain trees, such as oaks, poplars, and hazelnuts, where they exchange nutrients. The most sought-after varieties are the European white truffle (Tuber magnatum) and the black truffle (Tuber melanosporum), which fetch extremely high prices. Because they are hidden from human sight, their collection depends entirely on an animal’s ability to detect the unique compounds they release into the soil and air.
The Biological Attraction
The pig’s remarkable ability to find truffles is rooted in a specific biological mechanism, particularly in female pigs, or sows. Mature truffles emit volatile organic compounds to attract animals that will dig them up and disperse their spores. For centuries, this powerful draw was attributed to androstenol, a steroid structurally similar to a sex pheromone produced in the saliva of male pigs, or boars. This chemical mimicry suggests that the truffle’s aroma is misinterpreted by the sow as a sexual signal, triggering an intense desire to locate the source. While androstenol was the leading theory, other research suggests that the sulfurous odor of dimethyl sulfide may be the primary volatile compound that attracts both pigs and dogs to the black truffle. Regardless of the exact molecule, the sow’s powerful olfactory system registers the scent as a potent, irresistible cue, compelling her to dig for the buried fungus.
General Foraging Fungi
Outside of the specialized hunt for truffles, pigs are opportunistic omnivores that will consume a wide variety of fungi encountered during their natural foraging. In the wild or on a free-range farm, pigs use their snouts to root through the topsoil and leaf litter in search of food. They routinely eat common above-ground mushrooms, along with roots, tubers, insects, and small vertebrates. This general consumption of fungi is driven by nutritional availability and their natural instinct to root for any palatable food source. While they will eat many mushrooms, this is a distinct behavior from the deliberate pursuit of truffles. Pigs may possess a natural discernment, often avoiding many of the toxic mushrooms that grow in their environment.
The Shift from Pigs to Dogs
Despite their incredible natural talent, pigs are rarely used for commercial truffle hunting today, having been largely replaced by trained dogs. The main logistical problem is that pigs love to eat the very thing they are supposed to find. Once a sow locates a truffle, the intense pheromonal attractant makes her determined to consume it immediately, often requiring the hunter to physically restrain her to save the valuable fungus.
Furthermore, pigs are large, difficult to transport, and their powerful rooting action causes substantial damage to the delicate underground network of fungal threads, or mycelia. This damage can severely reduce future truffle yields in that location, which led to the practice being outlawed in Italy in 1985. Dogs, such as the Lagotto Romagnolo, are easier to manage, do not naturally crave truffles, and can be trained to simply indicate the location with a pause or a paw, allowing the hunter to excavate the truffle with minimal damage.