THE FABLE
OF OLD BLUE Consider the hypothetical case of Old Blue, Malthound
extraordinaire. Blue was perfect; sound, healthy and smart. On week days
he retrieved malt balls from dawn to dusk. On weekends he sparkled in malt
field and obedience trials as well as conformation shows, where he baited
to - you guessed it- malt balls.
Everybody had a good reason to breed to Blue, so everybody did. His
descendants trotted in his paw-prints on down through their generations.
Blue died full of years and full of honor. But what people didn't know was
that Old Blue, good as he was, carried a few bad genes. They didn't affect
him, nor the vast majority of his immediate descendants. To complicate the
matter further, some of those bad genes were linked to genes for important
Malthound traits.
A few Malthounds with problems started showing up. They seemed
isolated, so everyone assumed it was "just one of those things". A few
declared them "no big deal". Those individuals usually had affected dogs.
All in all, folks carried on as usual.
Time passed. Old Blue had long since moldered in his grave. By now,
everyone was having problems, from big ones like cataracts, epilepsy or
thyroid disease to less specific things like poor-keepers, lack of
mothering ability and short life-span. "Where can I go to get away from
this?" breeders wondered. The answer was nowhere.
People became angry. "The responsible parties should be punished!"
Breeders who felt their programs might be implicated stonewalled. Some
quietly decided to shoot, shovel and shut-up. A few brave souls stood up
and admitted their dogs had a problem and were hounded out of the breed.
The war waged on, with owners, breeders and rescue workers flinging
accusations at each other. Meanwhile everybody carried on as always. After
another decade or two the entire Malthound breed collapsed under the
weight of its accumulated genetic debris and went extinct.
This drastic little fable is an exaggeration--but not much of one.
Here's similar, though a less drastic example from real life. There once
was a "Quarter Horse stallion named Impressive. The name fit. He sired
many foals who also exhibited his desired traits. But when they and their
descendants were bred to each other, those offspring sometimes died.
Impressive had been the carrier of a lethal single-gene recessive trait.
No one knew it was there until they started inbreeding on him. The
situation of a single sire having this kind of drastic genetic effect on a
breed became known as the "Impressive Syndrome".
Many species and breeds of domestic animals, including dogs, have
suffered "impressive Syndromes" of their own. But cases like that of
Impressive are only the tip of the iceberg. A single-gene recessive
becomes obvious in just a few generations. But what about more complex
traits?
This is not to say that those popular sires we so admire are bad
breeding prospects. Their many excellent traits should be utilized, but
even the best of them has genes for negative traits.
The problem is not the popular sires, but how we use them. For a
century or more, inbreeding has been the name of the game. (For purposes
of this article, "inbreeding" refers to the breeding of dogs related to
each other and therefore includes line-breeding.) By breeding related
individuals, a breeder increases his odds of producing dogs homozygous for
the traits he wanted. Homozygous individuals are much more likely to
produce those traits in the next generation.
When a male exhibits a number of positive traits and then proves his
ability to produce those traits he may become a popular sire, one that is
used by almost everyone breeding during his lifetime, and maybe beyond,
thanks to frozen semen.
Since the offspring and grand-offspring and so on are good, breeders
start breeding them to each other. If the results continue to be good,
additional back-crosses may be made for generations. Sometimes a sire will
be so heavily used that, decades hence, breeders may not even be aware of
how closely bred their animals are because the dog no longer appears on
their pedigrees.
This is the case in Australian Shepherds. Most show-line Aussies trace
back, repeatedly, to one or both of two full brothers: Wildhagen's
Dutchman of Flintridge and Fieldmaster of Flintridge. These, products of a
program of inbreeding, were quality individuals and top producing sires.
They are largely responsible for the over-all quality and uniformity we
see in the breed ring today - a uniformity that did not exit before their
birth nearly three decades ago.
Working lines have also seen prominent sires, but performance traits
are far more complex, genetically and because of the significant impact of
environment. They are therefore harder to fix. Performance breeders will
in-breed, but are more likely to stress behavioral traits and general
soundness than pedigree and conformational minutiae. The best working
sires rarely become as ubiquitous as the best show-line sires. Not every
popular sire becomes so because of his ability to produce quality
offspring. Some have won major events or are owned by individuals with a
knack for promotion. Such dogs may prove to be wash-outs once their get is
old enough to evaluate. But a lot of breeders have been using the animal
for the few years it takes to figure that out and the damage may already
have been done.
Use of even the best popular sires, by its very nature, limits the
frequency of some in the breed gene pool while simultaneously increasing
the frequency of others. Since sons and
grandsons of popular sires tend to become popular sires the trend
continues, resulting in further decrease and even extinction of some genes
while others become homozygous throughout the breed. Some of these traits
will be positive, but not all of them.
The owners of Old Blue, the Malthound in
the opening fable, and those who owned his most immediate descendants had
no idea what was happening under their noses. They were delighted to have
superior studs and even more delighted to breed them to as many good
bitches as possible.
Dog breeding and promoting is an expensive
proposition. One usually winds up in the hole. But owning a popular sire
can change that. The situation looks like a winner for everyone--the stud
owner finds his financial burden reduced while breeders far and wide get
to partake of his dog's golden genes.
No one breeding dogs wants to produce sick
dogs. A small minority are callous and short-sighted enough to shrug
genetic problems off as the price you pay to get winners, but even they do
their best to avoid letting it come to general attention. We need a total
re-thinking of how we utilize stud animals. No single dog, no matter how
superior, should dominate the gene pool of its breed. Owners of such sires
should give serious consideration to limiting how often that dog is used,
annually, through its lifetime and on into the future, if frozen semen is
stored. The stud owner should also look not only at the quality of the
bitches being presented, but their pedigrees. How much will the level of
inbreeding be increased by a particular mating?
The bitch owner also needs to think twice
about popular sires. If you breed to the stud of the moment and everyone
else is doing the same, where will you go when it comes time to make an
outcross?
Finally, the attitude toward genetic
disease itself has to change. It must cease being everyone's dirty little
secret. It must cease being a brick with which we bludgeon those with the
honesty to admit it happened to them. It must become a topic of open,
reasoned discussion so owner of stud and bitch alike can make informed
breeding decisions. Unless breeders and owners re-think their long-term
goals and how they react to hereditary problems, the situation will only
get worse. ________________________________________
C.A. Sharp is the editor of the "Double Helix Network News". This article
was printed with permission and may be reprinted provided it is not
altered and appropriate credit is given.