Does any evidence support the contention that dry, extruded food is
better on teeth than bones?  There is ample evidence that dental wear
(the wearing down of the teeth caused by hard particles in the diet
abrading the tooth) is statistically more significant in carnivores
eating dry, extruded food compared to a natural diet that includes bone.
Dental attrition (the formation of wear facets) occurs at the contact
points of teeth.  Dental wear is not a function of occlusion, but of
diet.  This trend was first observed in ferrets as early as 1977 by
scientists able to distinguish wild polecats from laboratory ferrets,
based on tooth wear and plaque.  Wild polecats, even older ones, had
virtually no plaque and little dental wear, making the distinction
between them and ferrets a simple task.  The difference between the
two groups was diet; wild polecats ate a flesh-based diet that included
bone, while ferrets were fed a dry food similar to modern pet diets.
 
My own research confirms the finding.  I can mix wild polecat and New
Zealand feral ferret skulls with those from American pet ferrets of the
same age, and EASILY separate them based on dental wear and presence of
plaque.  The older the ferret, the easier it is to determine.
Carnassials used to consume dry, extruded foods tend to be worn from the
tops (crowns) downwards towards the roots, resulting in teeth with
flattened tops.  Carnassials used to render flesh and bones tend to be
worn from the wear facet at an angle towards either the buccal (cheek)
or lingual (tongue) side, resulting in teeth with sharpened ridges.
The only major difference between the two groups is diet.
 
The idea that a soft diet causes dental disease is a myth.  A major
health concern for pet carnivores eating a hard, crunchy diet IS plaque
and gingivitis!  Carnivores, including ferrets, that eat nothing but
animal carcasses have very little plaque buildup (2% or less).  There are
a number of factors involved in the formation of plaque, including the
inclusion of starches (sugars) in the diet, food stickiness, a lack of
abrasiveness, oral pH, calcifying agents, etc.  Hard to believe, is it,
considering pet food manufacturer claims that a hard, crunchy diet fights
plaque?  Then why is tartar STILL a serious problem in animals that eat
a diet entirely composed of dry, extruded food?  The reason is kbble
contain tremendous amounts of carbohydrates.
 
Ultimately, the use of dry, extruded food to prevent dental plaque is
the dietary incarnation of a tautological argument; it is circular and
self-supporting in nature.  A) Dry, extruded foods are popular because
they are touted to remove dental plaque.  B) The ferret uses their
carnassials to cut the hard food into chunks small enough to swallow,
creating a number of small and large fragments.  C) Large fragments are
swallowed, but small crumbs that remain in the mouth are softened by
saliva, ultimately forming a soft, sticky, white matter rich in
carbohydrates.  D) The white matter is soon calcified into plaque in the
presence of bacteria, dissolved minerals, and saliva.  E) To remove the
plaque, the ferret is fed a dry, extruded food, repeating the process.
The initial hardness of dry, extruded foods helps abrade some of the
white matter from the tops of the teeth, but it removes little from the
sides and bottom.  In other words, dry, extruded foods are the ultimate
cause of the problem they are advertized to prevent.
 
Wild polecats and feral ferrets have a low rate of tooth fracture and
only a very small number have dental plaque and gingivitis.  Pet ferrets
have a high rate of tooth fracture and a large number have dental plague
and gingivitis.  Of all the environmental differences, two stand out:
diet and caging.  The damage to ferret canines is probably due to caging.
For plaque and gingivitis, I think it is clear the problem is diet.  What
is especially significant is that wild and feral ferrets that consume
bone on a regular basis have significantly less dental damage than pet
ferrets crunching kibble.
 
Bob C
[Posted in FML issue 4160]