Re: [PyrNet-L] SAS. threat to Pyrs??

[JGentzel@aol.com]

In a message dated 12/22/99 11:34:34 AM Eastern Standard Time, 
Kshoffman@aol.com writes:

<< Keep in mind, this paragraph was in context with the rest of the post.  
That 
 is, with complex polygenic modes of inheritance such as threshold type 
 defects, and impairment of fitness traits that results from an accumulation 
 of suboptimal alleles over time, linebreeding can hide for generations what 
 is going on genetically.  This is because like pairs of involved deleterious 
 or suboptimal alleles are gradually being accumulated over each generation, 
 until it reaches the point where the level of impairment becomes obvious and 
 "visible" to the breeder.  A breeder may have no indication that this is 
 happening *until* fitness is noticeably impaired, or until the threshold is 
 crossed that results in expression of a polygenic defect.
 
 These statements are not based on one or two references, but on a vast 
amount 
 of written material I've collected and studied over the past two years based 
 on recent research in genetics and related fields.  This has involved 
 literally hundreds of hours of research on my own personal time, as well as 
 over a year of participating on the Canine Genetics Discussion list, and as 
a 
 result of that forum, having the opportunity to consult with numerous 
 professionals in the field. >>

You know, Kelly I don't have a problem with what you are saying here.  I 
think we all know this although not able to express it as precisely as you 
have done.  The old breeders who defined linebreeding always prescribed 
outcrossing ever "X" generations to "refresh" the gene pool and add vigor.  I 
think in more precise terms they were actually attempting to counteract what 
you speak.  The question before us in not whether one should only linebreed 
or the other side of the coin always outcross.  The question is is 
linebreeding harmful to the breed.  The answer is moderation in all things 
and only linebreeding will not result in good fortunes in the breeding 
program.  But a skillful use of linebreeding and that includes going out as 
required should.  Since you have already pointed out that we never know all 
that is there and there are "drifts" and mutations, this is the art of 
breeding.  That is were many of us fall short.  

<<We are now paying the price for this as evidenced by our rate of epilepsy 
in 
the breed, which can anecdotally be traced back to just a few dogs that 
everyone bred to, forsaking all others, one of whom can easily be classified 
as the "father of the breed." >>

I am a little confused, but think you speak of Belgium' s  here.  I will just 
add that IMHO, the current problem other that the occurrence of Epilepsy is 
the really shabby neglect of breeders to the problem.  I think some want to 
desensitize the issue enough that it is accepted as something that cannot be 
avoided.  Ever hear the mantra "Don't throw the baby out with the bath 
water."  That is their battle cry.