The Bernese Mountain Dog (German: Berner Sennenhund) is a large-sized breed of dog, one of the four breeds of Sennenhund-type dogs from the Swiss Alps. Bred from crosses of Mastiffs and guard-type breeds, Bernese Mountain Dogs were brought to Switzerland by the Romans 2,000 years ago.

The name Sennenhund is derived from the German Senne ("alpine pasture") and Hund (hound/dog), as they accompanied the alpine herders and dairymen called Senn. Berner (or Bernese in English) refers to the area of the breed’s origin, in the canton of Bern.

This mountain dog was originally kept as a general farm dog. Large Sennenhunds in the past were also used as draft animals, pulling carts. The breed was officially established in 1907. In 1937, the American Kennel Club recognized it; today, the club classifies it as a member of the Working Group.

The Bernese mountain dog is a large, heavy dog with a distinctive tri-colored coat, black with white chest and rust colored markings above eyes, sides of mouth, front of legs, and a small amount around the white chest.

The Bernese is one of the short-lived dog breeds, compared both to other breeds of a similar size and to purebred dogs in general. The average life expectancy of a Bernese Mountain Dog is approximately 7 to 8 years.

The Bernese's calm temperament makes them a natural for pulling small carts or wagons, a task they originally performed in Switzerland.

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