6. Cooked bone is harder than fresh bone, so more dangerous.
 
FALSE.  There is a tremendous amount of misunderstanding regarding what
happens when bone is cooked.  A remarkable amount of zooarchaeological
literature exists regarding the effects of cooking on bone, studied to
understand human evolution and diet.  For the sake of simplicity, we can
limit the discussion to two types of cooking: wet and dry.  Dry cooking,
such as roasting, baking, frying, cooking over an open flame, etc., has
four major effects on bone.  First, it drives off water attached to the
bone mineral, changing its basic structure and generally making it
harder.  Second, it oxidizes carbon compounds within the bone (the
cartilaginous matrix), burning them away or weakening them significantly,
reducing flexibility.  Third, long-term heat shrinks bone, resulting in
longitudinal and horizontal splitting and cracking, and exfoliation of
the outer layers of compacta.  Last, if the heat is high enough or long
enough, the hydroxyapatite can melt and recrystallize, forming compounds
with different physical properties.  In general, dry cooking results in
bone that fractures easier, has reduced pliability, and has sharper edges
and points.  Bones that have been subjected to dry cooking become quite
hard, and will preserve for millennia.
 
Wet cooking, such as pressure cooking, boiling, and stewing, is a
different bowl of soup.  First, because most meats and fats are slightly
acidic (about pH 4.5 to 6), boiled bones are exposed to corrosive agents
that cause pits, cracking, and exfoliation of the outer cortical
surfaces.  Interestingly, these dissolution changes are similar to those
caused by gastric acids in contact with bone surfaces, although not as
extreme.  Additionally, as hot water is forced into the bone during
cooking, it dissolves the minerals and denatures proteins that bind
calcium salts within their matrix.  This causes a tremendous amount of
bone deterioration.  Bones that have been boiled are lighter, chalkier,
and unable to withstand the same physical stresses as fresh or dry cooked
bones.  If boiled long enough, bones will decalcify to such an extent
that they can be smashed into a paste with fingertip pressure.  Anyone
who has boiled chicken knows how soft the bones become.
 
But, the point is moot (see bone eating argument, which applies to all
cooked bone).  Moreover, what happens when YOU bite down on a small
bone fragment?  It hurts your tooth, so you spit it out.  Ferrets do the
same thing, as do all carnivores.  The structure of teeth in specific
carnivores regulates the degree of pressure that can be applied to any
tooth before it cause pain within the pulp cavity, at the apex, or to the
peridontal ligament.  Hyenas have massive, thick teeth, so they can apply
more pressure before exceeding the pain threshold than a ferret with
thin, blade-like teeth.  Nonetheless, BOTH will stop chewing the instant
it hurts.
 
The implications are ferrets will stop chewing BEFORE they break their
teeth on bone.  That is not to say teeth are not injured on bone; all it
means is that ferrets have good judgment about what they can and cannot
safely chew (in terms of tooth pressure, not bowel obstruction!).
 
Ferrets, like all carnivores, actively chew the ends of bones, and
generally discard the shafts.  This is because the end of bones, the
epiphysis, is constructed of spongy trabecular bone covered with a thin
sheet of dense cortical bone.  The shaft of bones, the diaphysis, is
constructed of a thick, dense cortical bone.  Cortical bone is extremely
hard, and few carnivores attempt to consume them.  Ferrets are no
different; they will readily eat the ends off bones, and then hide
the hard shafts, but rarely attempt to consume them.  I have studied
thousands of chewed bones from dozens of species, including polecats,
feral ferrets, and pet ferrets, and they all eat bone the same way.  They
start at the soft ends and then work toward the middle.  Once the shaft
of the bone becomes too hard to chew, they abandon the task.  Boiled,
fresh, or roasted, once chewing a bone starts to hurt the tooth, the
ferret stops gnawing.
 
Bob C
[Posted in FML issue 3941]