Thanks for responding guys. I'm really just learning to use this type of forum so it took me awhile to find your responses. I don't get on here every day. Anna 66 ,I really know what you mean about being owned by a Rottie. I don't know if I can bear to get another, yet I don't know if I can stand to NOT have one in my life.

Dragondawg, I appreciate your input also. I've read about the genetic links and I've researched hybrid vigor because my other two dogs are mixed breeds, but both large. What can I say? I love the big guys, but they sure seem to have longevity problems. A friend of mine has such a good attitude about it. She says, "Yes, it's sad when they don't live long, but think of what a good life you gave them."

Meanwhile, I guess I'll just try to use common sense and do the best I can for my guys.