This is the only method provided by the current Italian law and it is generally considered the best.
It requires you to own a dog specially trained and developed sense of smell.
You have to keep it constantly in training and make him follow a special diet so that it maintains its skills over time. It also requires a space where to keep it, a way to bring him into the woods though, given the size of the animal, a car and a cage is enough, finally maintenance costs must be considered, such as feed, vaccines etc..
The research is carried out releasing the dog in the truffle bed and following it, being prepared to stop him when it detects a point of interest digging or standing above.
By the special “vanghino” (little spade) before you try to dig the soil lightly to make certain the presence of the truffle, once identified you cut the ground around and you leverages to bring out the truffle.
Just picked you cover the hole to keep the ecosystem as intact as possible.
Naturally the dog will be rewarded with biscuit or something that it likes.
Generally the dog identifies the exact point and finds a product at a good state of maturation, except for some cases with dogs particularly sensitive and with a great flair.
More often you go to hunt truffle in the woods more will be the feeling between the dog and the truffle hunter, and greater will be the possibility to find truffles.
Obviously it is not a machine, so it can wrong and indicate places where there is nothing, and it can’t work for too many hours because it gets tired, especially in the summer and you need to take it only in cool hours (otherwise the dog gets tired quickly by the heat and more it confuses smells of the soil).
Unfortunately, there are unscrupulous people that for their own reasons scatters the ground with poisoned meatballs and often you hear of dead dogs for this unpleasant practice.
For more details about this method, you can read THIS ARTICLE.