The Mountain Mastiff is a hybrid dog, also known as a designer dog. The Mountain Mastiff is a cross between the Bernese Mountain Dog and the Mastiff. It is not always possible to determine the characteristics, temperament or traits of a mixed breed. You will likely find the Mountain Mastiff has a combination of the characteristics found in both the Bernese Mountain Dog and the Mastiff.
I have just adopted one such puppy! I had no idea it was a recognized breed, only saw in his description Bernese Mountain Dob – Mastiff mix. So far, he does not exhibit the flat head of the mastiff, nor the wet mouth. He has brindle markings as a mastiff, but his fur is certainly much thicker than my pomeranians, though not quite as long as a Bernese. He is incredibly intelligent and thrives on treating our family as his “pack”