The Healthy Continuation of Breeds
The Demise of Typological Thinking
A Century of Nineteenth-Century Dog Breeding
Lessons from Population Genetics
New Structures for the Dog Fancy
A Healthy Balance, for Breed Identity
What is a breed? To put the question more precisely, what are the
necessary conditions that enable us to say with conviction, "this group of
animals constitutes a distinct breed?"
In the cynological world, three separate
approaches combine to constitute canine breeds. Dogs are distinguished first by
ancestry, all
of the individuals descending from a particular founder group (and only from
that group) being designated as a breed. Next they are distinguished by purpose or utility, some
breeds existing for the purpose of hunting particular kinds of game,others for the performance of particular tasks in
cooperation with their human masters, while yet others owe their existence
simply to humankind's desire for animal companionship. Finally dogs are
distinguished by typology,
breed standards (whether written or unwritten) being used to describe and to
recognize dogs of specific size, physical build, general appearance, shape of
head, style of ears and tail, etc., which are said to be of the same breed
owing to their similarity in the foregoing respects.
The preceding statements are both obvious and known to all breeders
and fanciers of the canine species. Nevertheless a correct and full understanding
of these simple truisms is vital to the proper functioning of the entire canine
fancy and to the health and well being of the animals which are the object of
that fancy. It is my purpose in this brief to elucidate the interrelationship
of the above three approaches, to demonstrate how distortions and
misunderstandings of that interrelationship now threaten the health of all of
our dogs and the very existence of the various canine breeds, and to propose
reforms which will restore both balanced
breed identity and genetic
health to CKC breeds.
In order for canine breeds to fulfill
their destinies effectively, the three distinct axes along which breeds are
distinguished must have equal importance and consideration, otherwise serious
problems arise. Breeds cannot be distinguished by ancestry alone, by purpose
alone, or by typology alone. Unless these three vectors of breed identity
interrelate fully and cooperatively, the fullness of that identity is missing
or marred. Unfortunately, this full and cooperative interrelationship is a
rarity in our contemporary dog world. The criteria of ancestry are applied
rigidly and mechanically; the criteria of purpose and utility are subordinated
or not considered at all; the criteria of typology are applied in a highly
exaggerated, obsessive fashion. The interaction of the three approaches is
seldom considered and almost never is a sustained effort made at the
integration of the three.
Canine breeds come into existence in many different ways and their
beginnings are very often shrouded in obscurity. Let it not be thought that the
three or four hundred-odd dog breeds now extant are the only ones possible, or
that there cannot be any more truly new breeds. Such is the genetic plasticity
of the dog that there is no end to the possible unique variations of which the
species is capable. New breeds are born and old breeds die periodically. The
genetic transformation of the dog goes on ceaselessly, and for that reason it
is impossible that any breed should remain frozen, with all its characteristics
fixed and unchanging, for any appreciable length of time. It must be realized
that canine breeds are manmade, created by artificial election out of the
endless diversity of the canine gene pool. Breeds must not be confused with
species or even subspecies, which occur naturally under the influence of
natural selection; dog breeds are only unstable manmade varieties which would
not survive unchanged in the natural world without human management.
An important characteristic of breeds is that they are created by
breeders -- not by registries or protective organizations such as The Canadian
Kennel Club. The origin and course of a canine breed is in the hands of its
breeders, first, last and always. It is the business of cynological
associations to facilitate and support the work of dog breeders and not vice versa. The purposes of the
Animal Pedigree Act, under which CKC is incorporated, are the promotion of
breed improvement and the protection of those who breed and purchase animals;
such is the mandate of the Act and therefore of the Club [Animal Pedigree Act,
§3(a,b)]. All else is secondary.
Ordinarily a breed has already existed for an appreciable length of
time before it reaches the point of becoming a recognized breed served by a
registry. Nonetheless, the event of its "recognition" by a registry
such as CKC is always a crucial one in the history of a breed. As things now stand, breed recognition is far more crucial (and
ultimately damaging to the welfare of the animals) than it need be or ought to
be, but more of that anon. First let us examine what is needed to start
a new and unique canine breed.
Four essential characteristics usually distinguish the origin in
the genetic sense of a new breed (as opposed to the discovery, popularization
and "recognition" of, for example, an autochthonous breed which may
have existed in a particular region for a long time without connection to
formal cynological structures). The first and most
crucial characteristic is the founder event in which a finite number
of individual canines is chosen to contribute genetic
material to found a new and unique canine population. They may all be quite
similar, or they may be widely divergent one from another (as when Bulldog and
Mastiff specimens were used to create the Bullmastiff breed). What matters is
that a finite and sometimes quite small number of individuals are selected from
the existing canine population and set apart so that their genetic material
alone forms the gene pool for the new breed. That is in fact the next
characteristic: isolation. If the founder group
continues to exchange genetic material at random with the general canine
population, a new breed will not result. Without genetic isolation of the new
founder group, the differentiation that creates a new breed cannot take place.
The logical consequence of this isolation is the next characteristic: inbreeding. If the founder group is of
small or moderate size, such inbreeding cannot help but occur. Even if the
founder group should be quite large, ordinarily those who guide the breeding
which creates the new breed will find it necessary at some stage to employ a
strong degree of incest breeding or inbreeding, to facilitate the weeding-out
of undesired characteristics and the fixation of desired traits. Particularly
if individuals of widely divergent type and physique are involved, inbreeding
will be required to set up a stable genome in which random variability is kept
within limits defined by the breeders. The final essential factor is artificial selection, since inbreeding alone will
not serve to fix type characteristics and to eliminate unwanted traits. The
breeders must select among the individuals produced in early generations so
that only hose displaying the desired characteristics are allowed to produce
subsequent generations. Without the four factors of the founder event,
isolation, inbreeding and artificial selection, new breeds ordinarily do not
come into existence. These four tools are used to define a new genome which, hopefully,
contains only the traits desired by the creators of the new breed and is able
to reproduce itself, with its distinguishing characteristics, to a fair degree
of stability and consistency.
Purebred dogdom is even now in serious
trouble through a general failure to distinguish between what is necessary to establish a breed and what
is desirable to continue that breed in perpetuity. Most registered breeds are
less than a century old as registered breeds; many are but fifty or sixty years
old. Yet nearly all breeds now show levels of expression of genetic defects
that must be considered unacceptable. Over 500 distinct genetic defects have
been cataloged in various breeds of purebred dogs and
more continue to come to light regularly. Some of these have reached very high
levels of incidence, creating problems for breeders and dog owners, threatening
the health of entire breed populations. What is worse, in many instances
organized control programs seem relatively ineffective. Although such programs
successfully identify affected animals, in some cases individuals with several
generations of "clear" ancestry stubbornly continue to produce
affected stock. Let us try to examine what has gone wrong and what must be done
to correct the situation.
First of all it must be recognized that practices which were
essential for the differentiation and establishment of a new breed may not
necessarily be desirable for its continuation over time and may in fact be
prejudicial to a breeds continued existence over the long term.
Let us take isolation, for example. Without genetic isolation, it
would not be possible to control the genome of a new breed still few in number.
It takes time and careful breeding to fix a new combination of characteristics;
while that is being done, the regular addition of new genetic material would
generally be counterproductive. Yet in the long term, if genetic isolation is
maintained, it will necessarily lead to degeneration through genetic drift.
Similarly inbreeding, if it continues to be practiced after the need for it is
past, will lead to a steadily increasing state of homozygosity
which may well destroy the genetic health of the new breed. Even artificial
selection, if carried on too strongly for too long, can combine with isolation
and inbreeding to reduce drastically the effective breeding population, thus
eroding the genetic health of the breed.
The present structure of The Canadian Kennel Clubs studbook
registry (and others like it) embodies a fallacy which is directly responsible
for the current genetic crisis in purebred dogs: the fallacy of breed purity.
The ideal of the purified lineage is seen as an end in itself; accordingly, the
studbook has been structured to reflect and to enforce that ideal rigidly and
absolutely. This insistence on absolute breed purity arises from
nineteenth-century notions of the "superior strain" which were
supposedly exemplified by human aristocracies and thoroughbred horses; this
same ideal, pushed to an illogical conclusion on the human plane, resulted in
the now discredited "scientific racism" of the Nazis, who tried
through selective human matings to breed an Aryan
superman. The idea of the superior strain was that by "breeding the best
to the best," employing sustained inbreeding and selection for
"superior" qualities, one would develop a bloodline superior in every
way to the unrefined, base stock which was the best that nature could produce.
Naturally the purified line must then be preserved from dilution and debasement
by base-born stock. There is no support for this kind of racism in the findings
of modern genetics -- in fact, quite the opposite: population groups that are
numerically limited and closed to new genetic inflow are now thought practically
certain to be genetically inferior. Certainly towards the close of the
nineteenth century it became embarrassingly obvious that the human
aristocracies of
The ideal of breed purity as applied to purebred dogs has resulted
at the end of the twentieth century in a subculture that holds
"purebred" registered animal stock to be qualitatively superior to
crossbred or "mongrel" stock. (The word "mongrel" is in
fact part of the vocabulary of racism, being applied equally to canine stock of
no recognizable breed, to animal crossbreeds and to persons of mixed race!) In
this subculture -- presided over in Canada by the CKC -- it is thought to be of
paramount importance that purebred stock be maintained unsullied by any genetic
influence external to the supposedly superior strains that are produced by
registered breeding in a closed studbook from a small group of foundation
stock. New members of the CKC are required to subscribe to "Conditions of
Membership" whereby they promise to have nothing to do with "dogs
which are not purebred" (with the exception of family pets and boarders),
"purebred" being specifically defined as referring only to dogs "registered
individually or eligible for registration in records of the CKC." Litters
which are made the subject of complaints that they may not be purebred are
investigated and in many cases ceremoniously withdrawn from the registry by
resolution of the Clubs Board of Directors. Whether you like
the word or not, this is effectively a special variety of racism in concept and
in practice.
Not all dog breeders are in agreement with the proposition that
breed purity is more important than anything else, particularly when they are
confronted with the problem of breeding dogs to demanding performance
standards. Mostly such dissenters are obliged to carry on their breeding
without the benefit of centralized pedigree record keeping and official
certificates of registration -- for example, those who breed "Alaskan
huskies", the high-performance racing sled-dogs that dominate both short
and long distance dogsled racing, keep pedigree records and maintain
sophisticated breeding programs, but only as individual breeders. Yet sometimes
even participants in established purebred registries engage in a subtle kind of
rebellion, quietly breeding according to their own judgment in defiance of
formal restrictions. Thus the Racing Greyhound Club of Australia, when it
recently subjected a broad sample of stock from its registry to DNA testing, is
rumored to have discovered that many pedigrees failed
to match DNA ancestry findings and that considerable interbreed crossing had
apparently occurred. Similarly most Siberian Husky
fanciers are aware that some CKC bloodlines may have received surreptitious
infusions of genetic material from non-purebreds or from other breeds. In some
circles one even gets the distinct impression that "its OK to crossbreed
occasionally if you have a good reason for doing it and you manage it in such a
way that no embarrassingly obvious mongrels are produced" -- i.e.,
"just don't get caught!" Thus the sanctity of breed purity may
sometimes be less than inviolate in actual practice.
Population geneticists insist that limited populations under strong
artificial selection, subjected to high levels of incest breeding - such as our
own CKC purebreds -- simply cannot maintain genetic viability and vigor in the long term without the periodic introduction of
new and unrelated genetic material. They are referring, moreover, to true outcrossing, the introduction of stock unrelated to the
breeding line, not merely the use of a dog which might be from someone else's
kennel but is derived from exactly the same foundation stock some generations
back.
DNA research has radically changed zoological concepts of species,
subspecies and varieties. In the nineteenth century and the first half of this
century it was thought that a species could be represented by a type specimen, that
the vast majority of individuals of a species were virtual photocopies of the
type specimen, genetically speaking, and that the genetic norm for most species
was homozygous at most loci. In the mid 1960s the credibility of that idea was
shattered as electrophoresis protein studies revealed extensive protein
polymorphism that had not been previously suspected [Carson 1983]. Today the
concept of a species in a satisfactory state of genetic health invokes a state
of "dynamic balance" in which the species genome contains an array of
genotypes with a high degree of heterozygosity, with
multiple alleles at many gene loci. Natural selection is now thought to favour heterozygotes in a way which tends toward a high state of
natural variability, preserving the greatest variety of possibilities with
which a species can meet new environmental challenges. Conversely, species
which have lost most of their genetic diversity, often through accidental
population "bottlenecks" similar to those which regularly occur in
purebred dogs, are held to be in high risk of extinction through the loss of
adaptive capability. (The most notorious example is the cheetah, which is
almost totally homozygous and is thought to have undergone at some time a
bottleneck reducing its population to a tiny handful of specimens.)
There is no reason why dog breeds also cannot be maintained in a
balanced state of heterozygosity, analogous to that
of healthy wild animal species, if typological thinking in the dog fancy could
somehow be replaced (or at least tempered) with population thinking. Fanciers
will generally admit that no dog conforms perfectly to its breed standard. Thus
the concept of the perfect type specimen, to which an entire breed ought to
conform as closely as possible, is really as foreign to dog breeds as it is to
animal species in the wild.
The fanatical pursuit of breed type to the exclusion of other more
important factors (more important to the dog, to his owner, and to his
veterinarian) has led to a distinctly unhealthy situation in most breeds. Since
the majority of breeders within CKC seem to direct their efforts toward the
production of a winning exhibition specimen, and since many breeders therefore
breed their females to the males that do the most winning at dog shows, a situation
has arisen in which continued effort to produce show winners leads consistently
to greater and greater exaggerations of "type", that being the factor
most susceptible to the off-the-cuff three-minute analysis of the breed ring.
It is an accepted fact that strong incest breeding is the fastest route to this
kind of "success"; here is one successful show breeder's recipe for
"excellence" [de Boer and de Boer, DOGS in
"My approach would be to
identify an outstanding, dominant stud dog. Let's call him 'Shadrack.'
To improve the odds I'd buy or lease three bitches whose grandsire on the dam's
side was the same as Shadrack's sire. Let's call the
grandsire 'Fashion Hint.' I would breed the Fashion Hint bitches to Shadrack. Assume, in this first generation, that I get
three nice bitches. For the second generation, I'd breed them to a half-brother
of these three bitches (Shadrack's son, also a
dominant sire). For the third generation, several 'mix and match' options
include going back to Fashion Hint or Shadrack. I
could also do brother-to-sister or father-to-daughter breeding."
Thus the quest for more and more refined breed type leads directly
to a state of advanced homozygosity, rising
inbreeding coefficient, low effective breeding population and consequent
impoverishment of the gene pool in most CKC breeds, through rampant
uncontrolled incest breeding.
The show ring has also been largely responsible for the decline of
breed purpose, working ability and temperament in a great many breeds, notably
sporting breeds, herding breeds and sleddog breeds.
The quick and easy gratification of blue ribbons and gilt trophies all too
readily supplants the hard work necessary to preserve and advance canine
working abilities. If our dog breeds are to conform to the ideal of "a
sound mind in a sound body" (as advocated by the proponents of the
Advanced Registry), the fancy must find some way of ensuring that less
dog-breeding takes place along the lines of least resistance and cheap
gratification, so that greater attention is paid to working characteristics,
temperament and trainability. A balanced outlook on breed identity must be
restored by integrating canine function with the ideals of conformation, beauty
and "type." All kinds of dogs, toy breeds not excepted, can perform
useful functions and respond to training. Those aspects of the fancy should be
accorded an importance at least fully equal to that of type and conformation
instead of being regarded as merely optional. For example, breeding and
exhibition of utility breeds such as gundogs and sleddogs
merely for sale as pets and for dog shows, with no effort made to maintain and
advance their working capabilities, is an obvious abuse which must lead
inevitably to mental and physical degeneracy in those breeds.
The breeder of domestic stock often assumes that he has abandoned
the realm of natural selection and that only artificial selection plays a
significant role in his breeding programme. Nothing could be further from the
truth. The breeder may attempt to abandon natural selection; natural selection,
however, will not abandon his stock. As one geneticist puts it:
"Man-imposed
characteristics, however, like the flower colours and forms selected by the
plant breeder, usually do not perturb the deep-set genetic variability systems
of the species. Most such changes are reversible when a less restricted gene
pool is restored. The 'balance' system appears to be retained by natural selection,
which, perhaps paradoxically, pervades most systems of artificial
selection."
(
Those who attempt to set aside the balanced genomes arrived at by
natural selection must struggle thereafter to attain and to maintain fitness in
their stock. There is more to this than mouthing platitudes about
"soundness." Artificial selection alone, such as that used to produce
winning exhibition dogs, involves breeding in a way which flagrantly disregards
most of the gene loci in the canine genome. Since genes assort in groups on
chromosomes (a phenomenon known as "linkage"), inbreeding and
selection for desired traits of superficial appearance unavoidably affect many
other genes which are inadvertently selected and often fixed in a homozygous
state in total ignorance of what is happening. This may be a major factor in
the current prevalence of genetic diseases. Thus natural selection, baulked for
a season by artificial selection, high-level nutrition, and advanced veterinary
care, reasserts its primacy at a deeper and more serious level when the new
genome as set up by the breeder proves flawed through genetic unsoundness, so
that healthy and hardy animals can no longer be produced, however typey and attractive to the eyes of the judges the result
may be.
Declining vigour caused by the inadvertent fixation of sublethal and subvital alleles
will not be made up for by breed points. Fitness criteria may not be replaced
with impunity by aesthetic criteria. The animal's environment is the ultimate
arbiter of its fitness and will not be denied its say. You may vaccinate the
dog and dose him with antibiotics, feed him with vitamins and minerals as you
like, enclose him in a sterile pathogen-free laboratory environment if it comes
to that! Still natural selection may not be avoided; it only emerges at a
deeper level. In a sense the dog's environmental
includes his own physical body; if the genes which blueprint his physiology are
flawed, then the dog is doomed regardless of his beauty and classic breed type.
The truth is that the "superior strain" cannot be produced by manmade
breeding programmes and artificial selection; the breeder's decisions are
subject to nature's veto at all times.
With what, then, will the breeder replace natural selection? If he
replaces it with profit, the degeneracy of his stock will in the end put him
out of business as veterinary costs and death eat up his profit margin. If he
replaces it with beauty contests, in the end his beautiful contest winners will
engender weaklings and degenerates. If he replaces it with screening programmes
for the "elimination of genetic defects," in the end his stock will
succumb to inbreeding depression as bitches fail to whelp naturally and puppies
die in the nest. If he replaces it with veterinary care, in the end his stock
will die prematurely of incurable cancer, or the young will fall prey to viral
diseases despite repeated polyvalent vaccinations. If he replaces it with work
and austerity, his stock may endure awhile longer, but in the end it will turn
out to be afflicted with genetic ills that slipped through his demanding
programme, or its performance will mysteriously decline as the inbreeding
coefficient creeps upward. In the end, natural selection cannot truly be
replaced with artificial criteria. The breeder must find a way to work with
natural selection, within the framework of what is now known about the
biological operation of the natural world. We in the canine fancy must begin to
take lessons from wildlife biologists, from evolutionary biologists, from
population geneticists.
In our quest for breed purity, the superior strain, and classic
type, we have made a sad mess of our dogs - with unhappy, neurotic
temperaments, epilepsy, blindness, deafness, immune system weakness, skin
diseases, blood disorders, endocrine system malfunctions, crippling blood
disorders, deliberate deformity, and often even the inability to reproduce
their kind without breeder and veterinary intervention. How clever we have been!
Can we not now take a clear-sighted view as the millennium turns
slowly over, of what we have done - of our own pitifully-flawed creation in our
world of purebred dogs and, like mature, intelligent people, clear away the
mess and try to do better? Can we not learn from bad experience? If we would be
truly clever, we might attempt to imitate more closely the methods of nature,
to work within the natural system, albeit for our own ends. That would indeed
be clever. I think that that is now possible, if we would but step outside our
own incestuous little purebred world and learn something of what people working
in other zoological fields of endeavour have already learnt.
How, then, may we set about correcting the accumulated errors of
over a century of what we might call nineteenth-century dog breeding? First of
all it might be wise to attempt a short-list cataloguing the errors and abuses
of which we are aware, the areas known to be deficient in one way or another.
Many of the abuses and deficiencies not rooted in outmoded attitudes
such as racism and elitism arise from misunderstandings of genetic realities.
Let us now examine briefly a few points of up-to-date genetic theory as they
relate to purebred dog populations.
Much of the work of population genetics involves estimating or
calculating gene frequencies, which quantify the relative commonness or
scarcity, within a particular population, of alleles at a particular gene
locus. If there is only one version of a gene in the population, then the
entire population is necessarily homozygous for that gene. Gene frequencies are
expressed as decimal fractions which must add up to unity, so a gene without
alternative alleles has a frequency of 1.0. The gene frequency figure is a ratio
of the number of copies of alternate versions of a gene in the population,
independent of the number of animals involved and of whether they have the gene
in homozygous or heterozygous form. An individual may have two copies of the
same allele or it may have one or none. For example, if a locus has two
alleles, and the population involved consists of fifty animals, and there are
25 copies of one allele, then the frequency for that allele is 0.25; therefore
the frequency of the other allele must be 0.75, with 75 copies of it in the
same population. It must be emphasised that gene frequency by itself says
nothing about relative heterozygosity or homozygosity; it deals only with quantitative aspects of
alleles in the population, not the diploid genotype of individuals.
Perhaps the most crucial concept in population genetics for dog
breeders is the founder event, for its theory describes perfectly what takes place when a breed is "recognised" by CKC or a
similar registry. Whatever may be the state of genetic balance or the frequency
with which particular alleles are found in the general canine population, it
all changes when a founder event occurs. In nature such events happen when
individuals of a species occupy and reproduce in territory new to the species,
losing contact with the source population of the migrants (as when small birds
are deposited by hurricane winds on mid-ocean islands). The founder event
describes the establishing of a small population, although later on it may grow
to be a large one. When a finite number of individuals found a new population
group, the genome of the new group will necessarily reflect the genes brought
to it by the founder animals; gene frequencies within that population will
reflect the gene frequencies within the founder group rather than that of the
source population. In this way, when a founder event occurs, a gene quite rare
in the source population may have a much higher frequency in the new
population; conversely, genes common in the source population may be infrequent
or even absent from the new population. It all depends on the genes of the
founders! Thus a genetic defect extremely rare in the overall canine population
can come to be common in a particular breed simply because one or more individuals
of a small breed foundation carried that gene.
The Hardy-Weinberg Principle states that under certain specific
conditions (random mating, very large population group, no mutations, absence
of selection pressure, for example), the relative allele frequencies of genes
at a given locus will not change from generation to generation and can be
described by an equation, allowing the geneticist to create a mathematical
model of gene frequencies within the population. Without trying to explain the
equation and its operation here, we can still say in general that the net
result is that heterozygote organisms will be much more numerous than homozygotes in a Hardy-Weinberg population. Many natural
populations can be described in this way, although purebred dog populations
cannot, since they are subject to inbreeding, artificial selection, non-random
mating and small populations. Nonetheless, the principle has a
certain significance, in that the overwhelming preponderance of heterozygotes in natural populations means natural
selection tends to favour the heterozygote. Thus the natural genetic balance
systems of most species include a high degree of heterozygosity
[
Small populations, such as most purebred dog breeds, are subject to
a condition known as genetic drift. This is a situation in which gene
frequencies change at random from generation to generation, varying from
statistical expectations because of sampling error. (Sampling error occurs when
too small a number of trials departs from the expectations of probability, as
when someone flips a coin six times and gets five heads and one tail - if he
flipped it 600 times, the results would be close to 300 heads, 300 tails, but
in a small sample, chance can cause a departure from the expected result.) This
happens also when gametes unite to form zygotes in reproduction; the union of
gametes is at random by hazard. A dominant black dog, whose dam was white, when
bred to a white bitch should in theory produce equal numbers of white and black
pups, but few breeders would be very surprised to see 2 whites and 6 blacks, or
vice versa. Yet when such sampling errors occur in small populations, over
subsequent generations gene frequencies can change, taking a random walk that
leads finally to the loss of one allele and the fixation of the other! The
smaller the population, the fewer generations this result is likely to take. In
a very large population, it will not happen at all. Genes are lost and other
genes fixed completely at random in this way by genetic drift.
Since in limited, genetically
isolated populations such as CKC breeds a certain amount of genetic diversity
is lost with each reproductive event through the action of genetic drift,
inbreeding and artificial selection. The number of
generations from the founder event becomes an issue. The average time between
one generation and the next is a convenient yardstick to help us realise the
relative rate of genetic attrition. A few instances exist in which certain
bloodlines - working dogs, usually - are bred conservatively enough that the
generation time is as much as an average six or seven years.
But this appears to be exceptional. Many exhibition lines seem to
operate on the following model: "Phoo-Phoo"
starts his show career at six months of age in Junior Puppy class, is heavily
"campaigned" and has all his Championship points by ten months of
age. The owners' immediate "bragging ad" in "DOGS in
The population figure that matters in situations such as random
genetic drift is not the total number of individuals alive at any one time. Nor
is it even, as one might think, the actual number of
individuals that contribute progeny to the next generation. Variations in
breeding population from one generation to the next have a marked effect, such
that the effective breeding population, especially where variations in number
are extreme, tends to be only modestly greater than the lowest number. Another
factor which makes a great difference and is crucially important in purebred
animals is the sex ratio of successful reproductors.
The effective breeding population can never be greater than four times the
number of males, no matter how numerous the females may be, since gametes must
come from both sexes. Thus anything that limits the number of males in use
drastically restricts the effective breeding population. Overuse of popular
sires is a tremendous factor in the genetic impoverishment of purebred dogs.
One of the major drawbacks of the proposed CKC Advanced Registry is the virtual
certainty that the existence and promotion of a few "elite" sires, titled,
temperament-tested and certified "clear" of major hereditary
diseases, will further dramatically reduce the effective breeding population in
many breeds, causing further declines in breed vitality and viability and
leading to the loss of vitally-needed breeding lines which happen not to be
among the elite group.
Genes found on the same chromosome will fail to assort
independently in accordance with Mendelian
principles. Such genes are said to be in a state of linkage disequilibrium.
This simple fact has a devastating effect in artificial selection, since it
means in practice that when a breeder selects for or against any single-gene
trait whatever, whether he is aware of the fact or not he is also selecting for
or against every other gene located on the same chromosome. This is how genetic
defects become rapidly fixed in inbred populations subjected to artificial
selection. Since dogs have only 78 chromosomes (diploid number) but many
thousands of genes, obviously linkage disequilibrium can be tremendously
influential. Genes that are linked eventually become unlinked over time (except
in certain special situations) through crossing over, a process whereby
chromosome pairs exchange segments of their DNA structure during meiosis. The
unlinking process however, is slow and unpredictable; it offers little hope of
remedying the linkage disequilibrium problem in a few generations and of course
is no help at all where deleterious alleles have already become fixed.
Situations exist in which a heterozygote individual enjoys a
survival advantage over both the recessive homozygote and the dominant
homozygote of the same gene; this is called overdominance
or heterozygote superiority. As yet not much seems to be known about this
mechanism and proven examples of specific overdominant
genes are rare. Nonetheless this mechanism may be one reason (apart from their
usually recessive nature) why genetic defects are persistently found in genomes
despite their apparent fitness disadvantage in the homozygous state. While on
this subject it is worth noting that population genetics offers mathematical
models for various forms of selective breeding, including the selective
elimination of individuals bearing homozygous recessive genes for harmful
traits. These models demonstrate that the elimination from the breeding
population of individuals homozygous for unwanted traits has only the smallest
effect in changing the allele frequency! It has been calculated, for example,
that to reduce the expression of the recessive albino gene in humans from one
in ten thousand to one in one million, simply by prohibiting albino (i.e.
homozygote) individuals from having children, would require nine hundred
generations of such selective breeding to accomplish! This is one of several
reasons why screening programmes, although perhaps profitable for the
veterinary profession, are of questionable effectiveness, since they identify
only affected (usually homozygous) individuals.
More commonly known as hybrid vigour, heterosis
is a situation in which a cross of two or sometimes three highly-inbred
bloodlines displays enhanced performance for some desired trait, as for example
higher yield in corn. It works best in plant species capable of
self-fertilisation, but has been amply demonstrated in domestic livestock
species. It is worth noting that in practice many different inbred lines must
be developed at the same time, that most of the inbred lines become so unfit
that they must be discarded as they become non-viable, and that considerable
random trial of different crosses must be done to establish which lines will
actually yield the desired result. Although the seed-grower's methods are
unsuited to purebred dogs, the overall principle is of interest, since it is
thought that heterosis works because of the heterozygosity of the hybrid generation, probably through
the action of both dominant and overdominant genes.
Geneticists are now starting to realise that the balanced-heterozygote systems
of many wild species involve a heterosis effect which
gives them a high degree of fitness.
As genetic variability diminishes and homozygosity
rises through inbreeding, a syndrome known as inbreeding depression sets in. It
is characterised by a reduction in viability (survival of individual progeny),
birth weight, fecundity (number of young) and fertility (reproductive success),
among other things. Much of it is caused by the homozygous presence of rare,
deleterious recessive alleles. Part of it may also be due to the relative
absence of overdominant heterozygote combinations. As
inbreeding depression becomes more severe, highly inbred lines tend to become
extinct through the loss of ability to reproduce successfully and / or
inability of the young to survive. It varies somewhat in intensity from species
to species, due probably to variations in the number and nature of lethal, sublethal and subvital alleles
involved. Some wild mammals which show almost no juvenile mortality when bred
in captivity without inbreeding, exhibit 100 percent juvenile mortality when
inbred! A survey of captive breeding records for 44 species [Ralls & Ballou, 1979, 1982] showed that juvenile mortality of
inbred young was higher than that of noninbred young
in 41 of the 44 species for which records were analysed.
The difference between the fittest genotype of a population and the
average fitness of that population is known as genetic load. [Muller, 1950] It
is, of course, caused by the presence of lethal, sublethal
and subvital alleles. The more such alleles found in
a population, the greater the genetic load. Genetic load is sometimes measured
by the number of lethal equivalents, and the severity of inbreeding depression
can be quantified in this way. Humans in general normally carry in a
heterozygous state from 5 to 8 lethal equivalents per person - genes or
combinations of genes any one of which, if homozygous, would cause the death of
the organism. It should be emphasised that genetic load is present in every
population, since never are all individuals maximally fit. The presence of
lethal, sublethal and subvital
genes is a normal state of affairs in all species. Homozygotes
for such genes are usually so infrequent as to have little effect on species
fitness. It is only when founder events and inbreeding occur that the gene
frequency of deleterious alleles rises and genetic defects start to become a
problem as the growing genetic load degrades the fitness of the inbred, limited
population. Thus in the case of purebred dogs the problem does not inhere in
the presence of "defect" genes, but in the registry and breeding
practices of the purebred dog fancy!
In recent decades growing evidence from DNA studies of protein
polymorphism conclusively disproved the "classical" view of species
as being homozygous at most loci, with the phenotypes of all individuals of a
species conforming to that of a type specimen. Population geneticists and
evolutionary biologists now realise that typological concepts are useless in a
natural world in which populations may best be described genetically not as
individuals conforming to a type but as arrays of genetic variability. Some of
the implications of the "balance view" are elucidated by one
geneticist as follows:
Species that are diploid and
cross-fertilised [this includes all mammals]... characteristically carry large
stores of genetic variability in a balanced state in their populations...
Genetic recombination naturally generates diverse genetic types from the large
field of variability in the gene pool. In order to meet environmental
challenges, natural selection in many such organisms tends to develop a system
based on the higher fitness of heterozygotes. These
are maintained under regimes of selection that exploit the advantages of heterozygosity for many alleles simultaneously. In these,
the large amount of genetic variability is continually being recombined as
balanced hybrid vigour is maximised...
The genetic system is not a
fixed and frozen entity but is dynamic and variable... By its very nature, this
genetic system is inimical to the perpetuation of sameness. At each
reproductive event an enormous field of genetic variability is produced. Most
of the variability is held in sexual populations by a complex balancing
selection based on the superiority of fitness of heterozygotes...
The biological conserver, short
of putting the DNA into liquid nitrogen, cannot hope to freeze the
characteristics of any natural population, be it a deme
(local population), a subspecies, or a species.
Efforts at artificial selection and breeding which attempt to defy
this system of balanced heterozygosity and
variability will almost certainly fall foul of the kind of difficulties we are
now encountering in purebred dog breeds. It is hopeless to attempt to freeze
the genetic characteristics of small populations and even the attempt, which is
doomed to eventual failure, is quite costly in terms of the loss of hardiness
and viability. Artificially selected populations, too, can and should be
maintained in a state of dynamic heterozygous balance. Thus the entire problem
of genetic defects would be minimised.
Assortative mating is a method of selective breeding capable of creating homozygosity for desired traits without having as great an
effect on overall homozygosity as does inbreeding. It
consists of mating phenotypically similar individuals
that are not closely related. This method of selective breeding would be
capable of maintaining a reasonable range of breed type in a balanced-heterozygosity breed system with an open studbook.
Having now acquired a few of the more crucial concepts of
population genetics, we are prepared to examine in a new light the
nineteenth-century system of dog breeding and registration which we have
inherited. As we prepare to enter the twenty-first century, perhaps we can
conceive a renewed system which will serve our dogs and their breeders far
better than the present one.
As we face the millennium, the one problem which most concerns the
entire purebred dog fancy is genetic defects. Breeders used to worry about
overshot/undershot bite and cryptorchidism. Not much
else of a genetic nature was cause for concern; fanciers were a lot more
worried about distemper, hepatitis and internal parasites. Breeding programmes
concentrated on individuals' visions of canine excellence. Then in the 1960s
the tip of the genetic iceberg emerged as concern grew about a joint disorder
called hip dysplasia. A control programme involving
the examination of hip xrays by a skilled scrutineer and the maintenance of a registry of animals
"cleared" of the defect was established at the
In December 1994, Time
magazine published a scathing indictment of the American Kennel Club and of
purebred dogs and their breeders, targeting in a cover story the problem of
genetic ills, suggesting that the best use of pedigree papers was for
housebreaking the puppies and recommending that the public satisfy its desire
for canine companionship with mongrels. Since then, most of us have known we
have an untenable situation on our hands. Our reputation as breeders of
purebreds is now in tatters; we are caricatured in the media as greedy,
uncaring producers of degenerate animals. The CKC's
main response to the situation was a Board policy statement that
"reputable breeders will provide a detailed written guarantee of the
present and future good health of the dog and will not hesitate to uphold their
guarantees." The policy statement, far from helping the situation, only
saddled breeders officially with a heavy responsibility without enacting
measures which might assist them in living up to it.
It is time for us as dog breeders to stand up for ourselves and for
our dogs, to reject the imputation that we ourselves are individually to blame
for the problem of genetic defects, and to demand swift remedial action by the
Club and, if necessary, Agriculture Canada. The crux of the problem is the
closed studbook and with it, the ideal of breed purity, the worship of type and
the preeminence of the championship show as goal and
arbiter of most breeding programmes. Armed with the concepts of population
genetics, we can now examine the last: century of nineteenth-century dog
breeding, ascertain what has gone wrong, and establish ways and means to
correct the situation.
Earlier we stated that the recognition of a breed by a registry was
a crucial event in its history, more crucial than it need be. That is because
the usual practice has been to open the registry to foundation stock for a limited
period, to inspect and register a small population of foundation animals, and
then to close the registry to new genetic inflow forever after, with the sole
exception of animals of the same breed imported from other registries and
derived from the same or closely-related foundation stock. In recent decades
there has usually been no unique Canadian foundation stock except in the case
of indigenous breeds; CKC merely accepts registered stock from other
jurisdictions. (Actually the relationship of CKC foundation stock to that of
other registries has never been clearly defined, so far as I know. CKC accepts
registration papers of other studbooks which it considers to be
"reliable." So long as the export pedigree shows three generations of
registered, numbered ancestry; import stock seems to be eligible for CKC status
without question. The criteria involved are clerical, not genetic.) Most of the
breeds we are familiar with were founded from sixty to over one hundred years
ago. In those days
The canine species possesses tremendous genetic diversity as a
whole. Like most species, that diversity includes a genetic load, a wide
variety of more or less deleterious alleles, probably quite a few of them held
in a state of heterozygote superiority, so that although natural selection
tends to eliminate homozygote recessives when they segregate, the bad alleles
themselves maintain a strong presence due to the selective advantage of the
superior heterozygote. What happens when a founder event occurs? Then it is
possible that bad alleles, uncommon in the canine population as a whole, may
achieve a much higher frequency of occurrence owing to their presence in a
small founder population - especially since the foundation stock of a
newly-recognised breed will already be considerable inbred from the breed
development process. Inbreeding and selection together raise homozygosity levels dramatically through the wholesale
elimination of alleles from the genome. Those alleles may be unwanted by the
creators of a new breed; nevertheless their elimination raises the allele
frequency of whatever remains.
Thus the recognition of a breed creates a founder event when the
registry is opened; a limited number of breed foundation animals are selected,
often from a population which has already undergone considerable inbreeding and
selection. Let us take for an example the Siberian Husky
breed. Registered in 1939, the initial CKC population consisted of 47 animals,
all belonging to or bred by one kennel! Of those 47, nine were foundation stock
of the kennel whose dogs were registered. Two of those were males imported from
In the case of the Siberian Husky, then, (which happens to be my
breed, with whose early history I am reasonably well familiar), The Canadian
Kennel Club opened a registry in 1939, inspected one kennel's dogs and admitted
four dozen closely-related individuals to the registry, which was then closed
permanently. No effort was made to ensure a broad foundation, nor a numerous
one, nor a genetically diverse one.
Just how permanently the registry was closed I recently found out
when I imported from
For the past fifty-six years, then, all Siberian Huskies bred in
Thus the original founder event in my breed plus the closed
studbook has resulted in a state of forced inbreeding for Siberian Huskies.
There is no such thing as an outcross mating in Siberians in any genetically
meaningful sense. A sire can be found, perhaps, who may have no ancestors in
common with a bitch for the last 5 or 6 generations - if one knows all Siberian
bloodlines well enough and doesn't mind going a few thousand miles to find him
- but he will not be an outcross, because all of his ancestors and all of the
bitch's ancestors are the same animals, once the pedigree is taken back far
enough. It would be difficult to calculate inbreeding coefficients for fifteen
to thirty generations of ancestry; software to handle calculations of that
nature doesn't seem to be generally available to breeders. (After all, a
thirty-generation pedigree would contain over two billion names.)
Thirty generations of breeding all going back to ten dogs or fewer
represents an impressive feat of sustained inbreeding! Predictably enough
Siberian Huskies, which eighty-five years ago were probably the toughest,
hardiest variety of dogs on earth, now suffer from the same gamut of genetic
defects that afflicts other breeds. Few if any registered Siberians are now
able to perform as sleddogs on anything approaching
the level of the 1910 dogs imported from
As a dramatic contrast to the foregoing example of the CKC's Siberian Husky breed foundation, let us examine for a
moment the standards which Agriculture Canada now applies to new domestic
animal breeds in this country, as set forth in a three-page leaflet entitled
"Establishment of a New Breed of Animals in Canada." Agriculture
The standard used for the creation of a new breed is as follows:
·
Minimum number of animals to
constitute the foundation stock of the new breed (F3): 200 animals (unique
genotypes).
·
In order to reach the required
200 F3 animals and in order to provide a sufficiently wide genetic base, it is
recommended that the minimum number of animals to be produced in each F level
be:
Fl : 60 animals
F2: 100 animals
It also stipulates that "the F3 generation is the earliest
generation to become eligible for inspection as foundation stock... In practice
most evolving breeds will evolve over many generations before having developed
a significant population of foundation animals."
These modern standards are at least somewhat influenced by
population genetics considerations, in an attempt to establish a basis for
genetic health and stability for new animal breeds in
Thus it is obvious that the Siberian Husky,
at least, could not begin to satisfy current Agriculture
Now I would like to evoke a vision of the future -- but not the
distant future. I want to describe how dog breeds might be in the twenty-first
century. Instead of all breeds being subjected to arbitrary structures not
equally well suited to them all, each breed would get whatever special measures
its breeders thought necessary. Instead of a fragmented canine fancy with
ghettos of show, fanciers, obedience buffs, and working-dog specialists, dog
breeds would have the benefit of a holistic outlook, integrating the various
aspects of canine: activity and producing well-rounded, versatile, mentally
stable animals. Let me stress that the suggestions which follow will be fully
practical and down-to-earth. They involve no technology we don't already
possess. They require no knowledge that isn't already generally available. All
that is needed is a proactive attitude and the will to make necessary changes
in an obsolescent structure. This vision could
become a reality within ten years time.
At the beginning of this brief I stated that the three distinct
axes along which breeds are distinguished -- ancestry, purpose, and typology --
had to relate fully and cooperatively, or the fullness of breed identity would
be missing or marred. Let me now describe how such a relationship might he
achieved.
To begin with, we absolutely must open CKC stud books, in every
breed, to new genetic inflow. There can be no long-term genetic health in small
populations such as our registered breeds without the periodic infusion of new
genetic material. The one big "sacrifice" we shall have to make, if
it is really a sacrifice, is to abandon racist attitudes and the concept of
rigorous breed purity. We must recognize that first of all, a dog is a dog,
species Canis familiaris,
and that is his true identity. He is a dog first, before he is a Siberian Husky or a Foxhound or a Doberman; breed identity is
subordinate to species identity. We must stop treating breeds as if they were
species, abandon the rigidity and narrow typological thinking which has heretofore characterized the canine fancy. We must
recognize that dogs are unique individuals and that there is no positive value
in trying to create groups of dogs which are all clones or photocopies of a
type specimen represented by a breed standard. This should not be too hard,
since breeders and judges have never been able to arrive at agreed and
consistent interpretations of breed standards anyway. Why, then, should we
pretend that a standard, which as it now exists evokes a different imagistic
interpretation in the mind of each individual breeder and judge, describes a
single ideal type?
Canine breeds can and should be differentiated, bred and maintained
on a dynamically balanced, heterozygous population basis without restriction to
a closed, historic founder group. The closed studbook and the breed purity
concept are, from a genetic point of view, simply unnecessary. Indeed, as we
have seen, from the standpoint of maintaining a genetically healthy limited
population, they are thoroughly counterproductive. Where is the logic in
submitting each and every CKC breed to a registry system which guarantees
ongoing, progressive genetic degeneration, loss of species vigor
and hardiness, and saddles every breeder with the unwanted, unhappy
responsibility of producing more and more unhealthy, flawed stock as time goes
by? The notion that genetic disease can be controlled, much less eliminated, by
screening programs and selection has not been borne out by general experience.
Those who promote such a notion are engaging in a cruel, self serving
deception. It may be that a breeder can sometimes improve his odds against
producing defective stock in a given mating by screening the parents, but
experience has proved that screening will not solve our genetic problems in any
wider sense. Despite generation after generation of "clear" stock,
bloodlines can still produce more and more affected animals. That is because
our problems are inherent in the closed studbook/incest breeding system. In
order to restore genetic health we shall have to adopt a different system.
It will be asked, "Just how will the opening of our studbooks
to outcross stock bring about the elimination of genetic defects?" The
answer is that it will not eliminate
genetic defects. That need not be the end in view. If we could somehow
eliminate all the various genes now known to produce harmful anomalies, plus
all of those yet to be discovered, we would almost certainly find that the
remaining genome was non-viable, that healthy reproduction and growth to
maturity could not reliably take place. Genetic defects are not
"eliminated" in nature. Instead random mating and behaviour patterns
that discourage inbreeding take care of the problem by ensuring high levels of heterozygosity and the consequent rarity of defective homozygotes. If we take steps to set up
similar patterns in purebred dogs, we shall be able to reduce the level of
expression of defective genes greatly, which is all that is
required. The end in view is healthy stock, not "racial
purity." Purged and purified bloodlines would be weak for other reasons,
as has been explained. As the mapping of the canine genome progresses and RFLP allozyme or microsatellite
"markers" for common genetic defects are found, we shall probably
then be able to use DNA studies to recommend matings
that will avoid the production of defective homozygous progeny -- provided that
we have made enough genetic diversity available through outcrossing
to give us the genetically distinct lines from which to choose! As things stand
now, most breeds are so homozygous that it could prove extremely difficult to
find matings which would avoid one genetic defect
without reinforcing another!
Very well, then, if we eliminate the closed studbook, how shall we
decide what stock to admit for registration? One must begin, of course, with
the existing body of registered stock. Thereafter, one way of proceeding might
be to strengthen and empower the breed clubs. They should be granted
responsibility and autonomy: responsibility for the welfare of their breeds,
and autonomy to make the judgments and decisions necessary to fulfill that responsibility. It should also be ensured that
the breed clubs are fully representative of all breeders, by making breed club
membership a requirement for anyone wishing to register stock he has bred or
imported.
The first task of the breed clubs would then be for each of them to
determine what sources of genetic inflow might best be employed in their breed.
Breeders alone can command the collective expertise to make that decision and
it ought to be theirs alone, but the designation of outcross sources should be
obligatory, not optional. The Siberian Husky Club of Canada, for example, would
have to decide where outcross animals might best be obtained for restoring heterozygosity to that breed; they might decide, for
example, that dogs imported from Russia and perhaps even an occasional
outstanding individual carefully selected from the present "Alaskan
husky" gene pool of racing sled dogs (which was derived largely from
1910-era Siberia imports that remained in Alaska) are two logical sources.
Breeds which do not have their origins in autochthonous populations would have
to seek outcrosses in similar related breeds, as Spaniels (English Springer)
and Spaniels (Welsh Springer), or Retrievers (
Advantage should be taken of DNA analysis techniques by using them
to monitor heterozygosity and relative kinship in
major breeding lines. (It would also be a good idea for the Club to offer DNA
profile parentage certification.) This technology already exists and is in use:
it is rapidly becoming much more affordable. Limits should definitely be set on
inbreeding, preferably by the breed clubs, but CKC should decide maximum
allowable limits of inbreeding as a default setting. Only by the outright
prohibition of excessive degrees of inbreeding will it be possible to make the
transition to a balanced-heterozygous state for purebreds; otherwise old ways
will continue through inertia and persistent typological thinking. Assortative mating can and should become the norm for the
preservation of type, mating individuals which are phenotypically similar but unrelated or at least not
closely related. The Club would have to monitor registrations, possibly
performing occasional DNA spot-checks, to ensure that inbreeding does not take
place; otherwise many would continue to breed from whatever dogs were in their
own backyard rather than seeking breed club advice to find suitable individuals
from unrelated lineage.
The responsibilities of the breed club should not end with the
designation of outcross sources and the inspection of outcross candidates. If
the fullness of breed identity is to be achieved overall in each population,
then the breed clubs should take on responsibility for balancing the various
facets of that breed identity. Realistic, meaningful and workable systems
should be introduced for monitoring temperament, for proving working ability
and trainability, and for evaluating, type and appearance. Championship shows
would then become breed-club events, since the methods of evaluation and the
various events required to test such qualities as temperament, vigor and endurance, working ability, and trainability
would be breed-specific and under the breed clubs oversight. That is not to say
that a number of breed clubs might not band together to stage events for
several breeds simultaneously at the same venue, but the all breed show with
all-rounder judges, under CKC rules for CKC Championship points, would
eventually be history. To ensure wholehearted support and participation by
breeders, it would probably be necessary for CKC to evolve some means of making
clear on the papers of every dog the extent to which that animal had been
submitted to the testing and evaluation procedures of the breed club and with
what result. Breed club input of information to the Clubs database could be
done by e-mail on the day of the event. Strong incentives for participation
should be arranged and breed clubs should be so structured that they could not
be autocratically ruled by individuals or cliques.
Registration certificates produced by CKC would carry much more
detailed information under the new system than they now do. The computer power
is now available to make this quite feasible. A certificate of registration
should once again carry a pedigree of at least four generations. A two-tier
certificate system would be necessary, as no dog would be eligible for breeding
registered progeny until it had been inspected and evaluated by the breed club.
Rating and measurement protocols are already being worked out by proponents of
the Advanced Registry proposal. Broodstock certificates should carry a summary of the breed clubs rating and
evaluation of the animal, together with evidence of proof tests for
temperament, working ability and trainability. All certificates should
identify outcross lines and bear a quantitative estimate of the relative heterozygosity of the animal identified by the certificate.
Breed standards would require revision under the new system. The
concept of disqualifications should probably be dropped in favour of a detailed
rating system in which all breeding stock would participate. In the case of
quantitative characteristics such as height and weight, a simple