One of the more serious problems that can affect canines is known as an "open fontanelle," which occurs when the skull bones at the top of the head fail to close. The problem is often found in conjunction with hydrocephalus, which is a condition in which too much fluid is found within and around the brain, placing pressure on the brain and surrounding tissues. Often the head will appear dome-shaped, and the open fontanelle is noticeable as a "soft spot" on the top of the dog's head. The fluid-filled spaces within the brain, known as ventricles, also become swollen. The increased pressure damages or prevents the development of brain tissue. 
Bones protect internal organs, such as the skull protecting the brain or the ribs protecting the heart and lungs . Because of the way that bone is formed, bone has a high compressive strength of about 170 MPa (1800 kgf /cm²),  poor tensile strength of 104–121 MPa , and a very low shear stress strength ( MPa ).   This means that bone resists pushing(compressional) stress well, resist pulling(tensional) stress less well, but only poorly resists shear stress (such as due to torsional loads). While bone is essentially brittle , bone does have a significant degree of elasticity , contributed chiefly by collagen . The macroscopic yield strength of cancellous bone has been investigated using high resolution computer models.