From: saavik@mentor.cc.purdue.edu (Marla Belzowski (K-9's))
Subject: Re: Catching-up!!
Organization: Purdue University
Date: Mon, 11 Jan 1993 18:27:38 GMT


Well after seeing quite a few articles on breeding and the methods used when
doing pedigree searches, I deciede to post this one again.  By the way
Cindy Tittle-Moore did a great job answering quite a few questions (well
I'm only about half way through all these posts so hopefully she didn't
post this one again.....oh well... better to have information overload than
lingering questions.)  Hopefully this will help some.....


Before Thanksgiving break I recieved e-mail from a few people
wanting to definitions and reasons breeders bred dogs the way
they did.  Well hopefully this will clear up some terms and misconceptions.
(by the way this is really lonnnnggggggg!!)

First the definitions:

1.  Outcrossing:  This is a breeding where the sire and dam are totally
unrelated, preferably for three or four generations.  The true form
of an outcross is between two entirely different breeds because in
reality the members of most registered breeds come from a common ancester.
(althought it may be many, many generations back).  It is very rare
for outcrossed puppies to be very uniformed in appearance.  Usually
there are a very large range of sizes, coats, colors, markings, and
other distinctive characteristics.  This does usually result in a
heterozygous litter (the pups have a wide range of genetic material
spread among them).  This does tend to produce healthier puppies, but
it is not always so.  Also, many of the desired characteristics of the
breed are quickly lost (meaning the pups are not usually show 
quality -- although there are exceptions!).  Also, these pups do not
tend to reliably reproduce themselves (which makes breeders even 
more broke).   If you are dedicated enough, you can eventually
continue breeding by outcrossing alone (but don't expect instant or
quick results).  You should pick dogs that complement eachother well
and are similar in general appearance.  This is a long hard road to
eventually developing a line.  Through outcrossing, many health
problems can quickly be eliminated (or just as quickly added into your
breeding), but usually you do sacrafice some show quality and
producibility.  You have to remember that dogs that appear totally
healthy may be carriers of genetic problems.  To find this out,
test mating is done to a dog that is affected with the genetic
problem (resulting usually in puppies that are both affected and
non-affected carriers) or by inbreeding to a related dog that also
doesn't show the signs of being affected (usually littermates are
used) this will usually result in some puppies free of the problem,
some puppies as carriers, and some puppies affected if both dogs
carry the problem gene (this is not as accurate as breeding to an
affected dog, but you are less likely to have to put all the puppies
down).

To me there are two types of out crosses.  One I call Linecrossing and
one I call Outcrossing.  A Outcross to me is a dog that has totally
unrelated dogs bred together throughout the entire pedigree.  This
is very rare in purebreeds.  Mauii, my collie, comes the closest to
this with only inbreeding in the fourth generation back on her pedigree.

Linecrossing is a form of out crossing were dogs from unrelated
lines are bred to produce a new line.  The sire and dam are usually
very linebred from their prospective lines and the resulting puppies
are vaired in appreance, usualy some looking like the sire's
line and some looking like the dam's line and some looking like mixtures of
both lines.

2.  Line breeding:  Line breeding is when the sire and the dam
are distantly related:  ex :   Grandsire to granddaughter,
Granddam to grandson, 2nd cousins, 1/2 cousins, Uncle to
niece, Aunt to nephew.....

Line breeding is the most common form of breeding in purebred dogs.
Though this breeding straigety, new genes are slowly introduced
and unwanted genes are slowly replaced.  This method sacrifices
little overally quality in terms of show quailty.  Usually the
puppies are rather close in general conformation.  The only problem
with this method is that it often takes several generations to
get the poor genes out, resulting in many puppies that have the
same genetic problems that their parents have.  Because some breeders
are more interested in winning, they do not place the
affected puppies on spay/neuter contracts.  This is both a blessing and a       
curse for the breed.  If the breeder is very carefull affected pups can be
used wisely to prevent loss of quailty, but still remove the affected genes
by only breeding the affected pups to known non-carrier relatives.  This way
the breeder can again try to "edit out" the bad genes.  It takes longer this way
but less show quality is lost in the process. This prcoess results in
dogs that will often reproduce their same quality.  This is refered to
as reaching homozygous litters (more genes of the same kind apparent
in the puppies).  

3: Inbreeding:  In breeding is were the sire and the dam are closely
related:  Mother to son, Father to Daughter, Sister to Brother,
1/2 sister to 1/2 brother, cousin to cousin.

It is the quickest way to find out what poor genes are in the line and
what dominant characteristics are in the line.  Although many
people are discusted with the idea of this family incest, it doesn't
cause the health problems that are commonly attributed to inbreeding.
If the genes for bad eyes are present, but hidden or resessive, this
will bring them out to their full extent.  If there isn't any 
bad genes, then the pupies will be of very close uniformity and 
very able to reproduce themselves (theroretically).  This is a
homozygous breeding.  The resulting puppies will have a lot of
genetic material the same as their parents and grandparents and
will be close genetically to each other.  This is what I call
"trying to get a carbon copy".  You are essentially trying to
put the genes from the grandparents back together to get a
carbon copy of the dog you had.  This breeding doesn't introduce
new genes and does not eliminate bad genes that the line already
has.  It only shifts them around like a rubix cube.  
This often results in litters with high show potential.

But there are drawbacks.  In-breeding exclusively will eventually
lead to infertillity.  It's like a xerox machine.  After so many 
copies, you have to renew the ink.  The same with dogs, you have to
introduce new genes.


Usually breeders try combining the three methods.  They will line breed for
two or three generations and then linecross (outcross).  Or they may
inbreed one generation, linebreed the next and then outcross.  Or like me,
I have a very outcrossed dam.  The sire I am looking at is a brother/sister
inbred dog.  Mauii should be highly recessive to the sire's dominate traits
while offering a large mixture of genes to promote a heterozygous litter
which will benifit the puppies' general health.  This breeding will give me
a good chance to get a show quality puppy while I still hang on to
Mauii's working dog body structure and abilities.  

The most crutial thing to each of these breeding methods is KNOWING what
your dog carries.  The most affective way to do this is to have your dog
checked.  Get the eyes checked, hips checked, blood tests, even genetic
screening (if it is possible).  Then go back and do your research.
Get the pedigree out and look up your dog's ancestors.  Find out if any of
them had a genetic problem or produced puppies that had genetic problems 
(indicating that they were carriers and you may have a hidden recessive gene).
The way to do this is to talk to breeders, and the "old-timers" in your breed.
The older members of your bred club are VALUEABLE sources of information.
You will have to pry some (no one likes to admit that their dog isn't
perfect).  

Test breedings would be nice, but then again, you waist time and can
end up with sickly puppies that have to be put down.  Genetic screening
is expensive and most genes causing genetic problems have yet to be totally
isolated. (but researchers are working hard).  Doing family tree searches
are relatively simple and rather effective, but it does mean long hours
of talking to breeders (which is usually fun anyway :) ), reading books 
(and books and books -- but this can be really stimlating intellectually) 
and doing calculations on probability.  

The local library should contain books on genetics for dog breeders, or
your local vet school should have a large selection.  If you really
want to learn about genetics, even introductory college level genetics
text books can help.  It also takes just a lot of paper-breedings (which
are really fun to do).   

I hope this has cleared some things up (and I hope I haven't totally
goofed up anything -- please post on if I did.)


--------------
Marla Belzowski   saavik@mentor.cc.purdue.edu
Mauii Nikki Belzowski CD CGC TDI CERF 
Brittish Legend fo Beowulf CD CGC TDI CERF  tri-color collies
Legend's Year of Jubilee    s&w collie



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