No big mystery. Bone broth is the latest hip term for beef stock. Any stock recipe will work.
A quick method. Take ten pounds of beef bones, put in a big pot, add water till the bones are covered by a couple inches. Bring to a boil, immediately skim any impurities, lower heat to a slow simmer or transfer to crockpot. Let simmer for four or five hours.
If you like, you can add some celery, carrots and onions for the last hour or so to pump up the flavor and a few spice if your dogs like that kind of thing. But basically it's just bones simmered in water until the water tastes good. Strain it, a little salt and it's Bone broth. Oh, and it's good for humans too.
