In the 1920s in Argentina, Antonio Nores Martinez started breeding a dog intended to not only be a pet and family guardian, but also a hunting dog capable of taking on big game such as wild boar and cougars.

Martinez picked the Cordoba Fighting Dog to be the base for the breed. The breed is extinct today but was described as a large and ferocious dog that was both a great hunter and fighter.

With the Cordoba Fighting Dog as the base, he then crossed in Great Dane, Boxer, Spanish Mastiff, Old English Bulldog, Bull Terrier, Great Pyrenees, Pointer, Irish Wolfhound and Dogue de Bordeaux.

Martinez kept improving the breed via selective breeding to introduce the traits that were desired. The first standard for the breed was written in 1928.

The Dogo Argentino is a large, white, short-coated dog with a smooth, muscular body, displaying both power and athletic ability.The minimum height for the male is 62 cm (24.3 inches) at the withers, for the female 60 cm (23.5 inches). Maximum height is 68.5 cm (27 inches). The length of body is just slightly longer than tall, but bitches may be somewhat longer in body than dogs. The length of the front leg (measured from point of elbow to the ground) is approximately equal to one-half of the dog's height at the withers. The head is powerful with a broad, slightly domed skull and a powerful muzzle that is slightly higher at the nose than the stop, when viewed in profile. Ears may be cropped, or hang naturally, close to the skull. The relatively short tail is set low, thick at the base and tapers to a point. The Dogo Argentino should be evaluated as a hunting dog, and exaggerations or faults should be penalized in proportion to how much they interfere with the dog's ability to work.

Dogos are known for being extremely loyal and affectionate with their families and crave attention from their owners. They are excessively tolerant of children due to their high pain tolerance, derived from selective breeding to be a big game hunter. They are protective of what they perceive as their territory and will guard it without fear against any intruder. They get along with other dogs as long as they have been properly socialized, but will usually not tolerate another dog trying to assert dominance over them and might not coexist peacefully with another dominant breed of dog. However, dog aggression is not desirable in the Dogo Argentino breed, as it is at odds with their intended purpose as a pack hunter.

Dogo Argentinos are accomplished hunters, and are widely used today and in a variety of ways from tracking, Search and Rescue, Schutzhund training, general police work including narcotics detection, military, to family dog. They are even occasionally used as a guide dog.

The Dogo Argentino was bred specifically to avoid the dog aggression problems inherent in the Cordoba Fighting Dog when applied to hunting, specifically its lack of ability to hunt in a pack. The creators of the breed intended that great care be taken to prevent this undesirable trait from manifesting in the Dogo Argentino, as the breed was always intended to be a pack hunter.

Dogos can develop an aggressive or dominant temperament if not socialized with other dogs at an early age, particularly with other dogs of the same sex, but can be trained by an experienced handler.

However, some Dogos are being bred by inscrupulous people for the sole purpose of dog fighting. The Dogos of these lines (unlike the original Dogo Argentino) are extremely dog aggressive and not suited for big game hunting. Additionally, the Dogos of these bloodlines are sought after for dog fighting because they combine strength and a willingness to continue fighting despite substantive injury. These Argentine Dogos are somewhat smaller than ones used for big-game hunting (Dogos involved in dog fighting are often between 75 and 90 lb.). In some rare cases, they are cross-bred with the American Pit Bull Terrier. In the United Kingdom it is illegal to own any of these dogs without specific exemption from a court. See Dangerous Dogs Act 1991 for details.

Text from en.wikipedia.org