Raw bones have naturally occurring enzymes which break down in a dogs soon as it enters the body. Which is the reason to never feed cooked bones because it has lost all its natural enzymes that is unrecognizable to a dog’s digestion system.
 
Bones are packed full of vital nutrients and help keep teeth and gums healthy, provide added nutrition and help cleanse your dog's digestive tract.
 
It is easy to understand why the dog wants the meat and marrow, but what makes the bone itself so desirable? The answer is that bones contain a huge number of nutrients that are vital to your dog’s health. 
 
These include:
minerals, including calcium, magnesium and phosphorous
protein-containing essential amino acids, including lysine
essential fatty acids
fat-soluble vitamins (A, D and E)
blood-forming nutrients (these are in the marrow), including copper and iron.
Bones keep your dog’s teeth and gums healthy
They provide your dog with exercise, strengthening their jaws and upper body.
They keep your dog occupied. Dogs that have a bone to chew are happier and calmer.
Bones provide great exercise, and help with mental health
 
Tips for Feeding Raw Bones:
Choose an appropriate size bone for your dog.
Always supervise a dog when it is chewing on a raw bone. 
Feed raw bones in an area that can be easily cleaned.
Dogs should never be fed a cooked marrow bone.