From: sbharris@ix.netcom.com(Steven B. Harris)
Subject: Re: In Defence of the Unofficial Live Doctor's Club (if people 
	suddenly became as healthy as their pets)
Date: 22 Nov 1996
Newsgroups: misc.health.alternative

In <19961122164500.LAA03133@ladder01.news.aol.com> davidharel@aol.com
writes:

>So preach no more pig Doctor, of your mineral fountain of youth!
>Our patients clearly do not need this, even if it is the truth.
>Can't you see how many jobs would go? You human Vet!
>If people suddenly became as healthy as their pets.


   David Harrell must have never owned a pet which lived to near the
end of its maximum lifespan.  Pets do (routinely) get grey and
arthritic.  They get infections and abscesses, heart failure and
diabetes.  You don't see an awful lot of this because most people's
pets are young-- without really good medical care, cats and dogs
generally don't live to be more than about 10 or 12 (equivalent in
human terms to about 50, no matter what you hear about the ratio of
7:1).*  Usually they don't make it that long.  And when they do get
blind, or get arthritis, hip dysplasia or heart problems, they get
taken to the vet for that special piece of vetrinary medical care which
you'd probably disapprove of if we doctors suggested it routinely for
chronically ill people.  How many of those people Wallace autopsied had
been put down?

   As for farm animals, don't make me laugh.  In age, most farm animals
are the equivalents of highschool kids.  Even so, they occasionally get
sick, as any practising vet will tell you.  Geez, didn't you ever read
any James Heriot books?

                                              Steve Harris, M.D.

* If you want to calculate the true physiologic "human age-equivalent"
of your dog, the first two years bring the animal to the human
equivalent of 15, and every year after that is about 4 in human terms.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: misc.fitness.weights,sci.med
Subject: Re: Harris shows off his pop view of dogs!
Date: 11 Sep 1998 08:29:20 GMT

In <35F83BD6.C8E4315D@tico.com> John Wash <j_wash@tico.com> writes:

John Wash <j_wash@tico.com>
in Message-ID: <35F83BD6.C8E4315D@tico.com>
states:

   >>Congratulations, you've just demonstrated your utter
unfamiliarity with the subject at hand.<<

    Rather the opposite.  But you had to put your foot in it,
didn't you?

  >> Perhaps you looked up the life expectancy of Deerhounds on
the AKC web site, or maybe you even have a copy of The Dog Book
(which is notorious for overstating the good traits of most
breeds).<

   No, I looked up on one of many Scottish deerhound websites, at
www.deerhound.org/growth.htm.  I can only assume that if Scottish
deerhound affictionados don't know how long the animals live, no
one does.  Not, not even you.

   >> The popular "seven years" concept has been pretty much
refuted.<<

    That's nice, because I did not assume it.  Stop putting words
in my mouth.  My comments about equivalent ages were based on
Pfizer canine life tables, and the veterinary literature.

  >> It is not a linear progression. <<

   I never said it was.  Though who knows what you mean by a
linear progression.  In a way, *after* maturity, there is a
proportional increase in mortality with time, between organisms.
This is a little difficult to put into words without the math
(Gompertz exponent factors are constant and proportional; each
species has a characteristic exponential rate constant).  But
basically it means that after maturity a year of aging for one
species or breed of animal is equivalent to x number of years for
another--- and that for the remainder of life into old age, this
ratio does not change.

  >> For example, in general, smaller breeds mature much faster
(at least in terms of reaching adult size) than larger breeds.<<

   Correct.  Aging, at least as defined in terms of risk of
mortality beginning to increase in an exponential fashion, does
not begin until puberty and most of growth.  In dogs that happens
at roughly a year for small breeds, at which time they are about
equivalent to humans at 15.  Large breeds are about at human age
12, and just entering the fastest development.  By two years
(equivalent to age 24 for small breeds, 19 for larger ones),
growth is complete.  Such comparisons are made by looking at
tooth maturity, bone epiphyseal closure, etc.

   After maturity, however, the Gompertz law takes over, and,
mortality risk doubles every 7 years in humans, and about every 1
to 2 years in dogs, depending on breed.  If you want a ratio
between dogs and humans for mortality doubling time it would, I
suppose, be anywhere from 4 to 7 years to 1, provided you *start*
at dog age 2 = human age 19-24.  Maximum life span for reasonably
large populations of dogs (and cats also) is about 20 years.
This corresponds to about 100 for humans (neither of these is
world record, but what you'd expect to be the max for a small
town).  Life expectancies (again) would imply a human/canine
ratio of as low as 4 in doubling time for mortality for the
longest lived breeds (eg, poodles), and as much as 11 for the
shortest lived breeds.

   >>Which means that, using your math and your multiplier,
smaller breeds have a life expectancy equivalent of 105 years,
hmm? <<

   You never saw my math, and you have no idea (or didn't until
10 seconds ago) what a proper multiplier for this might be, or
how one might use it.  Obviously, not all breeds have the same
one, and growth isn't complete at the same time in all breeds, as
you note.  That just means you start at a different place, when
comparing people to dogs.  Again, however, *after* maturity, a
reasonable mortality "doubling rate" multiplier as compared with
humans might be 4-5 for smaller breeds, and on the order of 10 or
more for the very large ones.  (Many medium sized breeds, such as
labrador retrievers, have excellent life expectancies, however.
As do standard poodles).  Of course, smaller breeds don't always
outlive larger ones-- it's only a tendency.  A breed by breed
analysis is necessary, and has only been attempted in a few
places.  Still, if you want some tables of very roughly
equivalent ages between humans and dogs of different size, you
can see them at

http://www.pfizer.com/ah/level2/petown/dogown/k9au.html

These folks study dogs for a living.  You don't.  The Pfizer
tables, btw, use a mortality rate multiplier of 4 from small
breeds and 7 for large ones, after maturity.  These figures are
averaged from life tables.  But the multiplier is than 7 for the
largest breeds.

   >>Look, there's just no good way to match up average human and
average dog life expectancy. There is such a huge variation
amongst breeds that any attempt to do it for the entire species
is doomed to failure.<<

    I never tried to do it for the entire species.  But there is
a range in dog breed life expectancy from roughly 7 to 13, which
corresponds with maximum life spans of roughly 10 to 20.  The
very large breeds don't usually last more than 10 years, so it's
quite easy to compare that with age 70 or 80 in humans (always
remembering to use populations of humans getting no better
medical care than the average pet).  The characteristic
exponential rise in mortality with age after full growth (or
puberty) is a feature of aging in nearly all iteroparous
organisms, and it's just a matter of constructing the life tables
and finding out what it is.  That's been done for dogs in some of
the references below.  I recommend them.

   >>Any time you want to go head-to-head with me on the subject
of dogs, little man, you just give a shout.<<

   Hey, don't look now, but that's what we've been doing.  You
seem to know nothing about the aging of dogs or any other
creature.  You're not familiar with either the geriatric
literature or the even the websites.  All you have is your little
dead dog stories.  Fine.  Tell them.

Regarding the Roberts vitamin C fiasco:

  >>You didn't prove anything. Bill wasn't wrong.<<

   "Wrong" is probably too kind.  His answer was meaningless, and
did not indicate that he understood the first thing about what he
was saying.  "No more than a few hours" is supposed to apply to
what?  "Vitamin C in the body" (what was asked about) does not
have "a" half life.  Different fractions of it have greatly
differing half lives.  Nobody asked "What's the half life of the
fraction of the megadose of vitamin C I just took that I'm going
to dump fast into my urine, until my body gets down to normal
levels?"  The answer to that, if it was even answerable, might
be: "That can vary from one hour to 10 hours or more, depending
on how big a megadose you took and how well your kidneys work--
assuming you were completely repleted to begin with."   But all
that's way too complicated for the conversation that actually
took place.  "No more than a few hours" is flat out wrong if it's
supposed to apply to everybody's megadose clearance.

   Also, this entire exchange totally ignores my other point,
which is that on one hand we have Bill saying he doesn't really
know the answer to a question, but he's going to give an estimate
anyway.  That's something he says nobody ever does in
misc.health.fitness.  Well, actually, you do.   And when you do,
being human, you screw up.  The problem is that you don't really
want to admit to being human.  You all think you're some kind of
transformer toys.  I haven't seen so much adolescent posturing
since I quit reading comic books.  A LONG time ago.


                              Steve Harris, M.D.


Eur J Med Res 1998 Feb 21;3(1-2):31-41
Geriatrics in canine and feline internal medicine.


Berl Munch Tierarztl Wochenschr 1996 Aug;109(8):292-303
[Life expectancy and cause of death in dogs. I. The situation in
mixed breeds and various dog breeds].
[Article in German]

Bottom line: life expectancy from a low of 6.8 years in the
Berner Sennenhund (that's St. Bernard to you, Wash) to 13.0 years
for the Pudel (even you can figure that one out).  Mixed breeds
did no better than purebreds.


Vet Rec 1997 Jul 12;141(2):40-44
Mortality in insured Swedish dogs: rates and causes of death in
various breeds.

Data on over 222,000 Swedish dogs of various breeds (250 of
them), which got good care because they were enrolled in pet care
insurance programs (a third of Swedish dogs).  The place to go
for the best stats.