Recreational bones - generally those that are sold under names such
as "soup bones," knuckle bones," or "marrow bones" - come from the
leg bones of large ungulates like adult cows, bison, elk, moose,
deer, etc. These are the weight-bearing bones of VERY large prey
animals, and are extremely dense bones. They also, almost without
fail, come seriously lacking in meat. What we end up with then is
merely a recipe for disaster. The bones are so hard and dense in
order to hold up such a massive animal, that they're frequent tooth
breakers. I can speak for many folks who have dogs that have
suffered in this regard - painful and expensive breaks, cracks,
wear, slab fractures.
The prey animal that these come from is just holding up so much
weight with that bone, and it's so very dense, that it's not
something that our carnivores are able to tackle safely.
Particularly when there's no meat on the bone to speak of from the
get go. Why bother? Even wolves have been documented as
consistently leaving these kinds of bones at the kill site unless
completely desperate with hunger. Our domestic carnivores never
need be desperate enough to have to settle for such a nutritionally
deficient and dangerous bone. Better by far to offer meaty, bone-in
items with bones that are at least theoretically edible.
The exception to the large ungulate weight-bearing bone "rule"
(although the bone itself is still inedible) might be something like
a beef shank with all the meat still on the bone. At least in that
case the carnivore actually gets a meal out of it and the workout
and tooth cleaning from tearing the meat off the bone, and then you
can just take the bone away once the meat is gone and before the
diner gets any ideas about playing hero on a tooth breaker "wreck"
bone.
I hope that clarifies why this list does not endorse the sale
of "recreational bones."