There's a lot of misconception regarding the nutritional value of meat bones and whether or not these are healthy for a dog.
There are essentially 2 parts to a bone: the actual bone and the marrow contained within it. You may be surprised to learn that 70% of just the bone itself is comprised of inorganic substances. The majority of a bone is a substance called hydroxyapatite, which contains 4 elements: calcium, Phosphorus, Oxygen and Hydrogen. Within this 70%, there are zero vitamins, protein, fatty acids or any other nutritional ingredients.
The remaining 30% is made of organic material. Almost all of this 30% ratio (about 95% of it) is made out of collagen, which is a fibrous protein that dogs do not digest very well. It is not absorbed by the body and usually passes through the dog's digestive system similar to the way that fillers in commercial dog food pass through without offering anything.
The rest (5% of that 30%) is made of Chondroitin Sulfate, Keratin sulfate, and Phospholipids.
The only two elements that have some nutritional benefits are the calcium and phosphorus. It should be noted that a high consumption of bone can cause constipation issues or very hard dry stools. The color of a Yorkie's stools will change if the dog eats a lot of this; there is often a gray color to the feces and if there are no constipation
problems, this is considered to be normal.
In regard to the marrow, this is found in varying levels depending on the bone. When a dog goes at a bone, chewing and gnawing, it is usually because he is after the marrow. It contains mostly monounsaturated fat and high levels of protein.
Most dogs find the marrow from bones to be very delicious; there are some people who eat this (mostly those on a Primal diet) and it is said to have a creamy texture and a subtle nutty flavor with a touch of sweet.
It is important to note that too much marrow can cause loose stools or diarrhea and this is another factor that must be considered since diarrhea is rather dangerous for toy sized
dogs like the Yorkshire Terrier that can quickly become dehydrated.
While this part of a bone can offer some benefits to a Yorkie, it is certainly not the only way to obtain it.