We have a mutt that we think is rott-mastiff-lab. He's marked like a rott, shaped like a mastiff (barrel chest, long legs) but has the size and temperament of a lab (85lbs, soft mouth, big sissy). We had a hell of a time getting homeowners insurance because he looks like a rott mix, and they are "dangerous breeds". This is the sweetest, least aggressive dog you'd ever meet. I could post videos of him letting our prematurely-weaned calico kitten 'nurse' from him. He's afraid of geese. The cats boss him around. Eventually we had a local am-fam agent come over and spend ten minutes or so with tyton and he decided that our dog was a lab mix, not a rott mix.