Milk Bones are not really good for dogs.
The milk bones that are made for dogs are made with a preservative that makes them bad for dogs as the preservative consistently produces tumors in lab animals.
While the FDA asserts that BHA is safe in low doses, dogs are being fed these tainted foods day in and out.
Milk Bones also contain wheat which, along with soy and corn, dogs have even more difficulty digesting than humans.
However milk bones are okay for dogs when fed to them in moderation but when feeding the dog milk bones in excess they may develop health issues including the tumors.
As long as your dog is eating regular dog food or other healthy foods then feeding the dog milk bones once in awhile is okay.
All treats for dogs can be bad in excess and even some dog foods are not the healthiest for the dogs you feed the dog food too.
But dogs have a short life anyway so it's not much of a concern.
Most dogs live 8 to 18 years at most depending on the dogs age so they should enjoy the treats as they will die regardless of what you feed them.