The Alpine Mastiff is an extinct Molosser dog breed, the progenitor of the St. Bernard, and a major contributor to the modern Mastiff (through such dogs as "Couchez"), as well as to other breeds that derive from these breeds or are closely related to them. M.B. Wynn wrote, "In 1829 a vast light brindle dog of the old Alpine mastiff breed, named L'Ami, was brought from the convent of Great St. Bernard, and exhibited in London and Liverpool as the largest dog in England." William Cavendish, 5th Duke of Devonshire, is believed to have bred Alpine Mastiffs at Chatsworth House.
The names "Alpine Mastiff" and "Saint Bernard" were used interchangeably in the early 19th century, though the variety that was kept at the hospice at the Great St. Bernard Pass was significantly altered by introducing other breeds, including Newfoundland and Great Dane, and it is this composite breed that now carries the name St. Bernard. Inevitably these Mountain dogs filtered through to the wider population, and the original variety dwindled in its pure form, though a rare breed, the "Cane Garouf" or "Patua", found in the part of the Alps formerly inhabited by the Alpine Mastiff, may also descend from the extinct breed.