one of my rottie has hard skin on legs..
I have two rottweilers.One of my rott having ths in legs.I guess she doesn't know how to sleep on floor.
It's too hard to touch.
What your dog has there are calluses caused by unrelieved pressure on her joints... exactly such as sleeping on a hard floor.
Rottweilers are big, heavy dogs and this will happen if they don't have the right kind of sleeping surface. I'd recommend getting both your dogs a good quality dog bed, preferably an orthopedic dog bed which is specifically designed to relieve the sort of pressure that causes this problem.
A good memory foam dog bed is the best choice, but any bed that is firm and can support your dog's weight properly without 'sagging' or 'bottoming out' will help.
Best of luck.