Rottweiler

My daughter adopted a male Rott from a good home where he had lived since birth. He was five when she got him and VERY overweight. My daughter died shortly thereafter, and I inherited him. He’s a good boy, although not tolerant of other dogs, and quick for such a fatty. He’s protective of me and absolutely loves children (which he had in his first supposed-to-be-forever home). He is so large that he cannot reach his own rear end, which makes him miserable. His stomach is huge. Other than the weight, he seems perfectly healthy. I like Dobies, and I’ve never had an overweight dog. I read all the columns, tried diet, tried exercise…he sits down and refuses to move after a half block and I can’t lift him…he’s well over 100 pounds. No matter how much or little he eats, he’s stays huge. Suggestions? Help? Is this a medical problem? I brush his butt for him, but I’m sure he would like to see it at least once in his life. He’s five now. He also wants to ride in my SUV with me, but he’s too big to get in. Poor baby. Thanks!