Tina M. Barber
5015 Shearing Road
Gainesville. NY 14066
Published in the GSQ in 1979
Much has been written about the science and art of Genetics.
money has been spent on experiments to prove this theory or that theory concerning the
inheritance of certain traits in animals. Unfortunately, most of this scientific work is
wrapped in a cloud of big words and college laboratories. It certainly would be nice to
cut through some of the haze and shed some practical light on this fascinating subject. In
fact, for dog breeders a basic understanding of the subject of Genetics is not only
interesting, it is essential.
Lets start at the beginning, and cover a few basic concepts and
definitions. There are a few terms which you need to know in order to link the scientific
information with observations made during the actual breeding of dogs. When I refer to
actual breeding of dogs, I'm speaking of my own observations which span more
than 20 years of breeding German Shepherds and evaluating over 2000 puppies. Later in the
article, Ill cover actual breeding experiences.
When animals mate, the resulting offspring receives half its genetic
makeup from each parent. This genetic material may be viewed as a string of physical and
temperamental characteristics which, once combined with the corresponding string from the
other parent, make up a brand new individual. This sounds simple enough, especially since
animals have been doing it for many years without our help. If we simply pick and choose
our Champions, and breed them with Champions, well get Champions, right? Not
necessarily! In fact, without carefully analyzing some hidden characteristics of the
parents, Champions or not, we are likely to get disappointing results.
These strings of characteristics I mentioned may be thought
of as boxcars on a train, with each boxcar carrying a single row of crayons of various
colors. The boxcars may be called chromosomes and the crayons inside the boxcars the
genes. The genes are the part responsible for the final characteristics, good or bad, of
the puppy. The chromosomes carry these characteristics from generation to generation.
The crayons (genes) from the stud arrive in the dam in a single line of
boxcars (chromosomes). At that time, they pair up with the dams corresponding line
of boxcars, and form a double line, like two trains of equal length sitting on parallel
tracks, side by side. To complicate things there is not only a corresponding boxcar from
each parent, but a corresponding crayon. Each crayon from each parent matches with one
from the other parent, forming a very large number of crayon pairs. Each pair of crayons
is responsible for a certain characteristic of the puppy (coat color, height. etc). The
puppy has this pair for life, and it cant be changed. To further complicate things
these crayons come in two sizes: full length and half length! And in a rainbow of colors!
Time to dig into those basic concepts. Each animal has an outward
appearance, a certain temperament and other physical characteristics. This is called the
animals Phenotype (pronounced FEEN-O-TYPE). This outward appearance is due to the
interaction of the crayons in pairs. These crayons may be in pairs of two shorts, two
longs, or a short and a long. The short crayons make up the recessive
characteristics and the long crayons, the dominant characteristics. If a pair
is made up of two longs, they will usually be crayons of the same color, and the puppy
will exhibit the characteristics of that particular color crayon. If the pair is made up
of two short crayons, they will usually be crayons of the same color, and the puppy will
exhibit that characteristic. The fun starts when the puppy inherits a short (recessive)
crayon from one parent and a long (dominant) crayon from the other, making a pair with one
long and one short. These are always crayons of different colors. The resulting puppy does
NOT normally show a characteristic which is between the long and the
short crayon. For example, an aggressive dog bred to a coward will not produce
a medium temperament. A tall dog bred to a short dog does not necessarily
produce a medium height. Many factors are at work here, and the offspring
resulting from the breeding cannot be expected to be a mixture of the two parents.
Assigning some colors to these crayons
may help. One possible color combination for this pair are: two blues, two greens, or
a green and a blue. Lets say the long crayon is blue in color for this particular
pair, and the short one is green. Assume, for the sake of the example that this crayon
pair controls whether the dog has three or four legs. A combination of two blues provides
a puppy with four legs. A pair of greens provides a puppy with only three legs. The pair
consisting of one blue crayon and one green crayon looks like it produces a pup with three
legs and a stump, but not so! The blue crayon totally overpowers (dominates) the green
crayon in the pair, and the puppy grows four legs, exactly like the pup with the
pure combination of two blue crayons! To the observer, the pups each have four
normal legs. There is no outward way to tell the puppy with the pure four legs
(two blues) from the one carrying the factor for three legs! This actual
genetic makeup of the pup is called the Genotype (pronounced JEAN-O-TYPE). In this case,
we have three possible genetic combinations, or genotypes: blue/blue, green/green, and
green/blue, and only two possible physical appearances, or phenotypes of those
combinations: normal four-legged dogs, and abnormal ones with only three legs.
So what is the big deal? If you want a puppy with four normal legs, and
you get a puppy with four legs, you have what you want, right? Not if you intend to breed!
Assuming you want to breed one of these dogs Ive been describing, and further
assuming you want to produce puppies with four legs, you would rather have the dog without
the short green crayon in the pair, even though his four legs look exactly the same as the
blue/blue dog. Although our example puppy has two parallel trains of boxcars for his life,
only one or the other individual train is passed on to his sons and daughters. Each parent
contributes one train (half the genetic makeup) to the next generation, producing puppies
with two full, parallel trains. Due to this, theres a 50-50 chance he will pass that
short green crayon on to the next generation, increasing the chance that the undesirable
three-leg factor will pop up in the future. Of the two described with four
normal legs, your best bet is the one with two blues. Since he will pass one or the other
of those blue crayons on to future generations, and since the blue crayon is dominant, all
future pups will have four normal legs, whether or not they inherit a short green crayon
from the other parent!
We are talking about the Recessive Gene Pool in bloodline.
The above example is simplified for the purpose of illustrating the procedure involved in
Dominant-Recessive transfer of genetic characteristics to following generations. Actually,
the process is quite a bit more involved, but it all breaks down to the basic principles
shown. There are factors hidden from view in all breeding stock. It is up to the breeder
to understand those hidden, or recessive characteristics before breeding.
But how do you figure out what they are? If they are hidden from view,
how do you determine the genetic makeup of an animal? Even the fanciest Genetics
laboratory at the largest university in the country cant look at an animal and
determine its genotype! How are we, mere breeders of dogs, supposed to know? That is the
basis of the next section.
First, it must be understood there is nothing
certain in this business of breeding. The whole concept of genetic transfer of
characteristics is based on the PROBABILITY that something will happen. Two poor specimens
bred together may produce a champion: two champions may produce a mutt. We must swing the
process in our favor, to increase the PROBABILITY that we will get what we want from the
breeding of two dogs.
Before we start we must face a unique problem, one which does not
usually face those college laboratory workers: the problem of working backward through a
pedigree. In the laboratory, two animals are bred together, usually producing a fairly
large number of offspring. Extremely detailed notes are kept, and all outward
characteristics (phenotypes) of the offspring are tabulated. These offspring are then bred
together in a random fashion, producing a very large number of babies. The same type of
detailed notes and tabulations are prepared on the phenotypes of those offspring. If the
number is not yet overwhelming, those offspring are again bred together in the same type
of random fashion, producing zillions of offspring. All the data from all these breedings
is available to the workers who bred the two original animals together. From this data, a
very accurate picture of the genotypes of the original pair may be constructed based on
the percentages of this or that physical characteristics in their offspring for the next
several generations. This is fine if you are working in a laboratory with very small
animals (like while mice or fruit-flies and you can house, feed. and examine all the
offspring for the next several generations. It is not normally practical for dog breeders
to do this.
As breeders, we must determine the genotype (or at least make an
educated guess) of an animal which occupies the position of one individual out of the
zillions produced in the fourth or fifth generation after the original mating.
We have a reverse problem from the laboratory. Where the laboratory workers know what all
the offspring of a single pair look like, dog breeders only know what a pups
ancestors look like. We can only speculate about the genotypes of our pups parents,
grandparents and great-grandparents. If we make a breeding error, a hidden characteristic
from the recessive gene pool in our stock may rise up when least expected. and produce
undesirable results. That type of breeding error is usually costly in time, money, and
quality of the breed, and must be avoided
The answer is to use the same technique as the old Riverboat Gamblers:
stack the deck! Know the genotypes, or producing ability, of the past generations on the
pedigree. This sounds like a simple statement of common sense, but is it really? Only if
those past generations have been carefully controlled by 'inbreed or
linebreeding as we call it, and only if detailed records of other litters are
available to you, the breeder. Just like the gambler, if you have a fairly good idea of
the value of the next card to be dealt you stand a better chance of winning.
By understanding the basic dominant-recessive concepts of genetics, and
with an adequate amount of homework, a breeder can make an educated guess concerning the
PROBABILITY of a particular breeding resulting in a desirable phenotype. Though nothing is
certain, its the best method there is for animal breeding, and can be quite precise if
By using selective breeding within specific lines of stock animals, the
breeder has a powerful tool at his disposal This tool permits him to see the expression of
undesirable characteristics, and to remove (cull) them before they spread. By removing
animals with these undesirable characteristics, the overall genotype of the breeding line
is improved and strengthened. By carefully monitoring or prohibiting breeding to animals
outside the bloodline, genes-- which may alter the carefully stacked deck are
blocked from entry. After a time, the undesirable factors can be eliminated, and a stable
line results. The Quarter Horse is an example of this, and is a result of approximately
200 years of intensive linebreeding and culling. This may explain why many reputable dog
breeders do not sell their best breeding stock except on co-ownerships. Control is the
Through linebreeding, desirable and undesirable characteristics become
predictable, or rather the PROBABILITY of getting a certain trait (long coat, three legs,
super intelligence, etc) becomes higher. Breeding stock carrying undesirable traits can
then be avoided. and the overall bloodline becomes stronger in desirable traits.
Eventually, the breeding stock becomes so strong in certain traits that breeding to
inferior stock still produces a desirable phenotype. Since most physical and temperamental
characteristics are controlled by the interaction of more than one pair of genes, this is
a very difficult point to reach. This point, usually reached
through a combination of 5% luck and 95% labor over the years, is
generally known as PREPOTENCY. The desirable factors of a stud or dam are passed along to
a majority of their puppies due to the lack of recessive genes which control the
undesirable traits. Everyone can think of a specific dog who passes a certain
characteristic reliably to his or her pups, almost without regard to the quality of the
But this is an ideal point which is seldom reached in practice. We are
still faced with the every-day routine of selecting breeding partners, and no breeding
animal is prepotent in all characteristics. Lets go back to the dominant-recessive
problem and make an example of the three-legged dog mentioned
This example will show how a characteristic
can stay hidden in a bloodline and pop up when least expected. With a little homework,
however, the source can be found.
Take a look at chart #1. We are holding a pedigree for a three
legged puppy. His parents both have four legs. His grandparents all have four legs. The
first three-legged dog on the pedigree is located in the third generation! The factor
skipped two complete generations and popped up in our puppy! If we do some homework, this
can be explained.
Chart #2 has the basic, raw information about the litters. At first
glance this doesnt tell us much but by analyzing the performance of each breeding
pair, we can make a pretty close guess about the genotypes of the parents and
grandparents. This litter information is critical to a full understanding of the bloodline
and its probable strengths and faults. Time spent gathering this type of information is
time well spent.
Chart #3 has the litter information broken down into probable
genotypes. This is not magic but an educated guess. Well go through each pair from
oldest breeding to youngest breeding, analyze each breeding pair based on their phenotypes
and performance in the litter produced and cover the logic of deducing probable genotypes.
Pair #1 produced ten pups, all with 4 legs. The sire is probably pure
(prepotent) in the 4-legged factor since, when bred to a 3-legged mate, all puppies had 4
legs. The dam, with 3 legs, certainly carries both short green crayons, and
therefore shows the trait that goes with that: 3 legs. Remember that the 3-legged factor
is recessive, and only shows up in the dog when both recessives are present at once. The
ten pups, though they have four normal legs, are not prepotent like the sire, but
now carry the 3-legged factor from the dam. Its almost a sure bet that all ten pups
from this breeding carry one long blue and one short green, and will pass one or the other
on to future pups.
Pair #2 produced 8 pups, all with 4 legs. Things are not so sure here,
since both dogs of pair #2 have four normal legs. These 8 pups may be pure (prepotent) in
the 4-legged factor, or they may carry a 3-legged factor. It is likely that most of the
litter is pure 4-leggedl. but not certain, since you know the factor is hiding in the
bloodline somewhere. Future breedings will shed some more light on this pair.
Pair #3 produced a litter that was split evenly between 3-legged and
4-legged pups. This is quite revealing. Since the 3-legged factor is recessive, the sire
of pair #3, though equipped with 4 legs, cannot be prepotent for 4 legs. The sire must be
carrying the 3-legged factor. Any 4-legged pup from this breeding is most likely
carrying the 3-legged factor. Any 3-legged pup is certainly carrying two short
green crayons which permit the recessive trait to appear.
Pair #4 is similar to Pair #2. All 10 pups have four legs, but there
may be a 3-legged factor lurking in some of the pups. Since all the pups have four legs,
one may be selected for breeding that carries the factor. This is another pair that
requires a look into future breedings in order to make an educated guess at the genotypes.
Pair #5 produced all 4-legged pups. Since the original mating of Pair
#1 produced puppies carrying the 3-legged factor, the sire of Pair #5 probably carries the
factor. The dam is a different story. This dog was selected from the breeding of Pair #2.
But since the mating of pair #5 produced no puppies with 3 legs, the dam is most likely
prepotent in the 4-leg factor. Though some of the pups from the original breeding of Pair
#2 may be carriers of the 3-leg factor, the pup selected as the dam of Pair #5 is probably
not a carrier.
Pair #6 produced 8 pups with 4 legs and 2 pups with 3 legs. This tells
quite a story about the pair, and provides some details on Pair #4. The sire of Pair #6 is
similar to the sire of Pair #5: a highly likely carrier of the 3-leg factor. Even though
he has four legs he is almost certainly not prepotent in the 4-leg factor. The dam of Pair
#6 also seems to be guilty of carrying the 3-leg factor. By chance, the dam was selected
from the litter for breeding, and happened to be one who carries the 3-leg factor.
Pair #7, a mating between animals with four normal legs produced a
litter with some 3-legged puppies. This certainly resulted from both sire and dam carrying
the 3-leg factor. Since each parent passes only one or the other crayon to the puppies,
the genotypes of the litter could be blue/blue, blue green. or green/green. Blue/blue
puppies and blue/green puppies look the same: four legs. Only the unfortunate ones which
inherit a green from the sire and a green from the dam will have 3 legs. Our pup is one of
After studying these example pedigrees all this may look pretty simple.
The basic concepts are simple and an understanding of them is crucial. You now can see how
undesirable traits can be carried through a bloodline and jump out generations
later when least expected. The probabilities of a characteristic showing up in a
particular puppy can actually be calculated mathematically, but thats outside the
scope of this article. If actual breeding is so straightforward and easy to calculate,
then why all the fuss?
Because its not so easy in actual practice. Although the basic
concepts of inheritance hold true when talking about individual pairs of crayons, most
characteristics are more complicated. Most of the time, more than one crayon pair is
involved, and there are several different dominant (tall) crayons and several recessive
(short) crayons, which may occur. There is often interaction between the different crayons
controlling a trait that causes a totally different and unexpected phenotype to appear.
Although it is possible to find certain characteristics that pass from generation to
generation in a manner similar to the example of the 3-leg and 4-leg puppies, this is the
exception. It is a constant task to analyze and select the best breeding partners in order
to purify the bloodline and increase the probability of producing a consistent, quality
So, we are faced with some problems. To minimize outside influence and
interference on our bloodline, we are restricting breeding to our own stock except in very
rare instances. There are strong points we want to keep and weak points we want to get rid
of. We do our homework, hope for the best, and then one day we find a Fantastic Champion
in the whelping box, surrounded by his so-so littermates. It seems that some of our hard
work has paid off! The 5% luck and 95% labor mentioned earlier finally produced what we
want (see Chart #4). Since we own both the sire and dam, we just repeat the
breeding and produce a hundred or so Fantastic Champions to fill the record books and put
our kennel on the map once and for good! We finally hit the jackpot, right? Not so fast!
Lets not count our Champions before they are hatched!
Remember the luck factor? And remember the Fantastic Champions
so-so littermates? It seems luck was certainly on our side there. A repeat breeding,
though it may be worth a try, probably wont produce another Fantastic champion.
Lets look at a technique, which will allow us to insert FCs strong points into
our bloodline, and possibly produce another FC! This may sound far-fetched, but we have
done this at Shiloh Shepherds at least three times on two totally different bloodlines.
This technique worked best with the particular bloodlines available to us. It serves to
illustrate how a dog may be recreated if the basic principles of heredity are
understood, the breeding stock is available to you, and the time is available for
At first glance, it looks like we should breed FC to the best looking
bitch we can find. Not so. Remember the dominant and recessive business? FC is probably
carrying a truckload of recessive characteristics from his unimpressive parents or
grandparents. Most of those characteristics are undesirable. If simply bred to a
good-looking bitch, we would most likely end up with those undesirable characteristics in
the puppies (maybe three legs!), and FCs strong points would be lost or diluted. In
this case, we use a technique normally reserved for experimental purposes to determine
genotypes: the back cross.
Back crossing takes an offspring and breeds it back to its opposite sex
parent. In this case, FC is bred to his dam. This may sound crazy, but weve done our
homework. Chart #5 may be used for reference during this example. The dams
sire was a super producer, i.e. prepotent in many areas. Even though the dam is plain, she
inherited many strong factors from her sire. By breeding FC and his dam, we are likely to
produce a litter, which exhibits a range of characteristics and qualities. Some puppies
will be strong in desirable factors; Some will be real losers. We take the best female pup
that resembles her sire (FC), and breed her to her sires sire or, if possible, to
her Looks Great Grandsire on her sires side, thus eliminating the
undesirable characteristics of the Pet Stock bitch. Once again. we select a
bitch from that litter which shows the phenotype we desire (probably her Grandsire) and
breed her to Super Producer on her dams side.
By this method, we have isolated and eliminated many of
the recessive characteristics we don't want and intensified the traits we want as
originally shown by Fantastic Champion. We have gone back into the bloodline on the
dams side to intensify the positive characteristics of the dams sire 'Super
Producer', and the dams grandsire Super Stud. By this time we should be
producing a puppy which resembles FC. If not, we must start the process over again on
FCs sires side. Chart #6 shows the final product of this method.
By using Chart #5 as a guide, try extending the pedigree
listed below, up to 8 generations. You will find that Super Champ shows up:
1 x in the 4th, 1 x in the 5th, 6 x in the 6th,
7x in the 7th, 5x in the 8th for a total of 20 times in 8
Even though it appears that Fantastic Champion is
lost, we have not lost the characteristics we desire. By using FC as an indicator of the
traits we want in our breeding stock, and isolating the side (dam or sire) which provided
those traits, we were able to identify the weak points and pool the strong points,
eventually resulting in a stud which was prepotent in the strong points. Our Fantastic
champion was a throwback to his Super Champ ancestors. Through this method,
those qualities are now available to us for future breeding.
Through the process of inbreeding or heavy linebreeding we have been
able to find the hidden recessive genes in our
bloodline. Since inbreeding intensifies the faults as well as the virtues, we are able to
put together a clear picture of the genetic makeup of our stock. For example, when we
actually produced litter C (on chart #6) we found a recessive for weak pigment and
straight fronts, which showed itself in a large number of pups. By using the best
specimens, the faults were hidden but were still present in the gene pool and
might have appeared later. To solve this problem, and eliminate these undesirable
recessives from our new stock, another breeding technique was used: Type Breeding.
Now for a few cautions. Never breed two dogs with an
open pedigree where all the dogs are unrelated and/or of different types.
Its similar to breeding a dog where all the ancestors come from different breeds of
dogs. In other words, the results of such a breeding are unpredictable. Opposites may
attract, but they dont produce anything predictable.
Be sure you know the difference between inherited and
"acquired" characteristics. A dog does not 'inherit a UD degree. He
acquired it through intensive training. The ability to learn, or the basic intelligence is
inherited. A puppy who loses an eye due to an accident will still produce pups
with two normal eyes. The injured eye is an acquired (so to speak) trait. The
dogs coat color, basic bone structure, and basic temperament are examples of
inherited characteristics, and may be passed along to future generations. The difference
between inherited and acquired characteristics often becomes very blurred. Be certain you
know the difference when evaluating breeding stock or selecting a puppy.
Have a specific Plan of Action when breeding. To use hit
or miss methods by breeding only to good-looking stock is inviting
heartbreak. A breeding program without a purpose is like a ship without a rudder or a
builder without a blueprint. It is even more foolish to base a breeding on faulty logic
and misinformation. For example, I have seen the mating of a SCH III and a champion in
order to get the best of both! Such a breeding produces the best of neither, and usually
is a disappointment.
Linebreeding has ancient roots. From the Bible, we learn that Abraham
was commanded by God to practice inbreeding and linebreeding. Abraham married his
half-sister and produced a son. Isaac. Isaac married Rebekah, his first cousin, and
through successive marriages between first cousins and other close relatives, the Jewish
nation was formed on the Abraham-Isaac line.
We have covered quite a bit from crayons to back-crosses. I hope it is
clear by now that this business of Genetics can be taken out of the laboratory and into
the kennel. Its not necessary to have two college degrees to use these ideas in a
sound breeding program. All thats necessary is basic understanding of the principles
involved and a willingness to experiment and learn from
successes and failures. I hope it is clear how a carefully controlled program of
linebreeding can improve a breed, and how adequate homework on litters produced by certain
pairs of breeding animals can be critical to your understanding of the recessive gene pool
in a bloodline.
PRINCIPLES OF GENETICS. Third Edition
By Eldon J. Gardner
John Wiley & Sons, Inc.
New York, NY (1968)
By Claude Villee, Warren F. Walker Jr., and Frederick E. Smith
W.B. Saunders Co.
Philadelphia, PA (1963)
ESSENTIALS OF BIOLOGY
By C. Leland Rodgers
Barrons Educational Series, Inc.
Woodbury, NY (1974)
The article you have just read was written back
in '79. It was published in the German Shepherd Quarterly and later I made copies of those
pages and used them in one of my Newsletters... and then again in one of our "best of
the best" editions. Some of you have already read it, some may not have, either way..
.its time to STUDY IT!! Dana has also prepared some interesting facts for you
(below) taken from old GSD books. I had planned to add a lot of "personal" data
to this list, since I knew many of those dogs in a much more "intimate" way, but
due to the lack of time it will have to wait for another lesson. I would really like to
see you....FUTURE BREEDERS...SPEND SOME TIME GETTING MORE FAMILIAR WITH THE DOGS WE HAVE
IN OUR PRESENT PEDIGREES!!!