Shih Tzu 17 Years Thorax Sagittal

The trachea of this patient is moderately bending to the right on the DV view. Why? How do you differentiate which is normal from a mediastinal mass?
Shih Tzu 17 Years Thorax Sx

Which is the anticlinal vertebra in this patient?
Shih Tzu 17 Years Thorax Dx

This patient has quite severely mineralized tracheal rings. This finding is often seen in an aged patient.