Bísara breeding pigs, of Celtic origin, are large animals, reaching over 1 meter tall and 1.5 meters from the base of the neck to the tail, with a black coat, white or with white spots, thick skin with long bristles, thick and abundant. The head is long and thick, with long hanging ears, face and a big mouth. The neck is long and muscular. The trunk is long, with an arched back, high chest, flat and shallow, long and short flank, a dropped close rump and little muscular and a pronounced belly.

In the early twentieth century the "vezeira" was put into practice, using large areas for feeding the pigs. The animals walked large distances eating from the oak trees, acorns and grasses they found. Today we can affirm that the Bísaro pig is reared in a semi-extensive system in which all breeders have pigsties where the welfare conditions for animals have been approved. These pigsties are characterized by the use of adequate areas for the development of animals in cages, with no gestation cages and all of them use the land adjacent to the parks where the animals are most of the time, except during periods of birth and lactation, in which mothers and piglets are found in maternity wards. Some farmers use the outdoor system (camping) throughout the production cycle, the use of shelters and maternity time in heated isolation. The Bísaro pig is exploited in four aspects, i.e., all farms are engaged simultaneously in raising sows, boars, piglets and in the fattening of pigs.

According to the Livestock Census of the mainland of the Kingdom of Portugal (1870), the definition of Bísaro is the name given in the provinces of central and northern kingdom to the esgalgado pig, piernialto ears and falls, to distinguish it from roundwood and piernicorto pork Alentejo. The Celtic name was used by Sanson to express the antiquity of this type of pig, which was the only one that existed in the Celtic peoples of ancient Gaul.

J.F. Macedo Pinto in 1878 in the Compendium of Veterinary wrote: (...) "Bizaro Type 1 or Celtic - The descendants of these breeds of wild and common boar belongs exclusively to Europe. They are distinguished by the following characteristics: head short and thick flat face, long snout, large mouth, large ears, which droop down below the line of the eyes, elongated body, arched back, chest with the vertical diameter much larger than the horizontal which gives them the boat-like shape, long legs, and black bristles with most individuals. The many races that are found throughout> Europe, mainly in the north hardly differ from each other by their degree of corpulence. Our common breed of pigs in the Northern provinces also enters in this type that has a slow development, completing their growth at 2 years of age and therefore it is difficult for them to gain weight. It gives good meat, but are very bony and atocinan little. (…)