There are four varieties of Swiss Mountain dogs, bred to be companions and working dogs for farmers in Switzerland. Two types -- the long-haired Bernese and the short-haired Greater Swiss Mountain Dog, both black with brown and white trim -- have become increasingly popular as family pets in the United States.
The short-haired Greater Swiss Mountain Dog is the larger, with males as tall as 28 1/2 inches (72 centimeters) and as heavy as 135 pounds (61 kilograms). The longer-haired Bernese may be slightly shorter and lighter. These dogs are gentle by temperament and usually good with children, and can be trained to pull carts or sleds. However, like other large dogs, Bernese mountain dogs wouldn't make good companions for apartment-dwellers [source: Dog Breed Info].
A couple of cautions: The Bernese suffered some from inbreeding a few decades ago, and can suffer from a variety of health problems as a result. In addition, they can sometimes be shy or overly sensitive, so choose one from a reputable breeder.
Both these dogs need good training. They need a lot of interaction with their families and are happier -- and better behaved -- when they have things to do. As with any giant dog, don't leave them unsupervised with small children.