From:
Bruce Williams, DVM
Date: 2001-03-31 00:34:00 UTC
Subject: Re: Dr. Williams - Experience begets Understanding?
--- In Ferret-Health-list@y..., "Brett Middleton" <brettm@a...> wrote:
> "Bruce Williams, DVM" <williams@e...> wrote:
> > The only way to generate valid data of this type would be to
split a
> > colony of ferrets in half - neuter 50% early, 50% late, and see
what
> > happens over a lifetime.
>
> Wouldn't it be even better to split the late neuters into two
groups,
> doing some prepuberal and some postpuberal?
Conceptually, sure! It would be even better to have cohorts
castrated at 4 weeks, 6 weeks, 8 weeks, etc. In the theoretical
world, we can do anything.
>
> An excellent point, given what's happened to research funding. It
> seems like you can't get a grant unless you're doing applied
science
> that's so far back from the frontiers of knowledge that you can
> guarantee success, and promise that somebody will make millions off
the
> results within two years. Yet, at the same time we're talking
about a
> problem that is definitely of economic importance, so there ought
to be
> a way to shake out the money *somewhere*.
But in the real world, it all comes down to economics. For this
study to be valid, we would likely need to maintain animals for a
lifetime (we could conceivably dispose of them after they got through
the Golden Age of Tumors - 4-6 years, but it would be immoral to
euthanize simply for expedience's sake.
Here is the economics: per diem (the cost to maintain a ferret in a
laboratory setting) at the AFIP (which is fairly cheap) is
$3.50/day. Multiply that one by 7 years per animal - you can see the
research expenses of such a study and why it is not really
economically feasible. Even if you were able to get per diem lowered
to $1/day - that's close to $3000 per ferret to maintain for the
period of the study. Without an upside of a product to market, as
you mentioned, most companies wouldn't even consider it.
Now this study could conceivably be done at a rescue facility, but
that means no adoptions, no feed changes, strict standardization of
variables, no introductions, etc. - once again a difficult
proposition.
> Which makes me hope that veterinary medical insurance for ferrets
> becomes *really* popular, because the insurance company would then
have
> the bucks to get this done, and a serious economic incentive to
fund
> research that would reduce their payout. (Or, they could simply
refuse
> to insure farm ferrets, which would give the farms incentive to
solve
> the problem, assuming that few people would want to buy an
uninsurable
> fuzzy.
It is more likely that insurance would not cover ferrets - the chance
of a farm ferret developing a life-threatening disease is way too
high. Dogs are safer - they generally last up to 17 years (at least
the small ones) and the chance that an owner will stop paying the
insurance after several years with no disease is much higher (sort of
like the way that health clubs make their moneyh - the vast majority
of people sign up after an encounter with a full-length mirror, but
stop going after a month or so.
> I'm still not convinced that we know any such thing about the size
of
> the initial gene pool, despite what our intuition tells us. And
our
> experience in establishing various breeds of livestock here seems
to
> show that we can produce large populations of healthy animals
starting
> from surprisingly restricted gene pools.
> It's a shame that we've got such good information on livestock
> importations going back to colonial days, but don't seem to have
> anything equivalent for companion animals. But, it seems likely to
me
> that there must have been a number of early ferret importations
from
> different sources, and that the various current-day farms would
have
> been drawing from somewhat different pools before closing their
> bloodlines. That makes it a little hard to believe that they all
got
> the same jokers in their genetic woodpiles, while small closed
> populations such as Australia did not.
> Yes, but at least in livestock, pedigrees are traced, and the
process of producing animals is far more scientific. In cattle, we
now have techniques of AI and in-vitro fertilization, which leads to
significantly more outbreeding than what occurs on most ferret
farms. Couple that with the fact that with the increase in Aleutian
and ECE, two very contagious diseases, the opportunity for bringing
in new bloodlines from outside a large facility is markedly decreased.
> > We also have a very high incidence of other diseases, such as
> > cardiomyopathy in American bloodlines.
>
> Again, do we really have a reasonable degree of certainty that
there
> *is* a true difference in the incidence rate of these diseases, or
are
> there simply differences in detection and reporting because of
> husbandry practices? Is it possible that American house fuzzies
are
> simply observed more closely, that we are more alert to these
diseases,
> and/or that we're more indulgent to our pets and thus more likely
to
> seek veterinary care for every sneeze and sniffle?
I can only go on comparisons with colleagues in these other
countries, who routinely give me "Aha, but we don't see that over
here". Of course, it is certainly the possibility of errant sampling
that may skew the data.
One thing that I always try to keep in mind is the fact that most
published veterinary literature on disease incidence is definitely
skewed by the collection process. Unless we are dealing with a
colony situation, where every animal is monitored, our data is really
quite fallible. For example, I am currently writing a chapter
dealing with 1540 neoplasms in my collection at the AFIP and from my
now-defunct company, AccuPath (a collection three times the size of
the largest previously published collection. Whereas I can say that
the ratio of hyperplasia to carcinoma of the adrenal is roughly 3:1,
it absolutely has to be realized that this represents a sample only
of animals whose owners had the foresight and the economic capability
to have a surgery performed, and may really not represent what is
going on in the total population. Of course, the more animals you
see, the more likely thatyou will get representative sample, so I
continue to collect, and collect.
With kindest regards,
Bruce H. Williams, DVM, DACVP
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