On some veterinary web sites there are short refutations to the growing
trend of feeding pets natural diets containing bone.  In such a rebuttal
on www.vetref.net, a veterinarian (Jan Bellows) cites a
yet-to-be-published paper (by Cecilia Gorrel) that quantifies dental
injuries in wild large cats (species not mentioned).  Bellows concludes
that because the wild large cats eat a natural diet containing bone and
have broken teeth, then it is dangerous for pets to eat bone.  Remember
the discussion regarding damaged tooth frequencies?  Do you remember
when I argued veterinarians tended to use personal bias to determine
bone-eating risk?  Bellows argument is a perfect example of ignoring
data to support personal opinion.
 
Since the paper is unpublished, we have no way of knowing what is
actually being reported.  Nonetheless, I am prepared to admit that while
I have no idea of the actual numbers, there is a very real possibility
the data are correct.  In other words, I admit wild large cats probably
have beaten up, fractured and worn teeth, at least to the levels reported
in other, independent studies.  In the best of those studies, the
probability of an individual predator (averaged from all types of
carnivores) breaking at least one tooth during their lifespan was 0.25.
You can look at this number as meaning one out of four predators will
break at least one of their teeth during their lifespan.  This is an
extremely important number, so remember it later in this discussion.
 
Accepting that predators break teeth in no way means I concede the idea
ferrets cannot safely chew bone.  I have multiple objections to this
line of reasoning, and eagerly look forward to when the paper is finally
published (if ever -- the comment was posted in 1996!), simply because I
hunger to critically review it.  Why?  Because I know it is impossible
for the author to tie individual tooth injuries to specific events.  In
other words, although a wild large cat may eat natural foods containing
bone and they may have a broken tooth, before you can conclude one caused
the other, you need confirming evidence proving a direct, causal link.
The tooth may have been damaged jumping to escape predators, while
killing prey, from a fall, during a fight over territory or position, in
personal defense, from a bit of gravel accidentally ingested when eating
the prey, or a hundred other factors.  Or, more likely, it was broken
because of the accumulative effect of any number of factors, with no
specific one being to blame.
 
I also object to Bellow's argument because it lacks comparison to other
dental dangers.  For the sake of argument, assume wild large cats have
teeth roughed up by a bony diet.  How does that compare to dental
problems in house cats eating a natural diet?  Or those fed dry, extruded
foods?  Or those cats consuming a wet-food diet?  How does it compare to
polecats, or pet ferrets?  Have you noticed that with each unanswered
question, we gradually shift from a strong homologous model towards a
weak analog?  Assigning risk without comparison to other risks is
valueless.  Such comparisons may prove wild large cats possess damaged
teeth, but the degree and impact of that damage many be more or less than
house cats eating a dry food diet.  Careful comparison may show broken
teeth in wild large cats are NOT comparable to polecats, much less
ferrets.  This means, using this type of report to bolster the claim that
eating bone is very dangerous to ferret teeth, is hyperbole at the best,
and poor scholarship at the worst.
 
The greatest predicament in using dental problems in wild large cats
as a model for pet ferrets eating bone is simple biomechanics.  The
biomechanical impact on the teeth of a wild large cat attacking, killing,
rendering, consuming, and dragging away large prey are quite different
than those of a polecat doing the same thing to small prey.  This means
the forces acting on the teeth are different as well, making the
comparison valueless unless you can quantify those differences.
Fortunately, you don't need to know the specifics of biomechanics to
determine the probability of dental damage for any specific population of
animals.  All you need are a large number of randomly collected skulls,
and the patience to count the number of damaged teeth.  Hyenas,
specializing in eating the hardest bones, have the greatest probability
of damaging one or more teeth, more than 0.40.  Wolves, also habitual
bone eaters, have a probability of 0.29 for damaging one or more teeth.
Small cats and mongeese have a probability of 0.15 that they will damage
one or more teeth.  One Australian study found the probability of damage
to cat teeth was 0.20, but some studies of cats from more marginal
environments had higher probabilities.  No one has published tooth damage
probabilities in polecats (yet), but it should be less than or equal to
that of small cats and mongeese, with a probability of approximately 0.15
to 0.20.
 
Bob C
[Posted in FML issue 4160]