Re: [pyrnet] Dwarfism

[JGentzel@aol.com]

In a message dated 9/18/00 3:25:15 PM Eastern Daylight Time, 
woodskk@eburg.com writes:

<< Any dog with *a* carrier parent has a 50% chance of being a carrier.
 The
 possibility *never* declines and it cannot be diluted.  IOW, if a dog
 has a
 known carrier 10 generations behind, statistically it has a 50% chance
 of
 being a carrier.  The exact same statistical possibility as if the
 carrier
 were the parent of that dog.  A dog that has carrier "parents" (as in
 two)
 may well be a dwarf.  If it is a litter mate to dwarfs, its chance of
 being
 a carrier statistically rises to 2/3rds.
 However, any dog with a carrier in its pedigree has
 a 50% chance of being a carrier. >>

You can prove or disprove almost anything with statistics and this is a good 
example.  If a single dog was a carrier the percentages of the 1st generation 
offspring being carriers is 50%.  When this single dog is now 10 generations 
back and there have been no carriers known since, all the dogs theoretically 
would be 50%, but the other 50% non carriers would carry a 0% chance of 
transmission.  In ten generations there are 2046 descendants, so 
theoretically 1043 could be carriers, but 1043 could not be carriers.  The 
point is with dwarfs, if you breed wisely you can diminish or negate the 
possibility of the transmission of recessive genes going to the next 
generation.  I am not a mathematician, but the probability of the simple 
recessive carrier gene  coming up 10 times on a 50/50 chance get much less 
each generation.  The overall group (2046) will continue to be possible at 
50%, but I suspect the individual chances are far less.  This is all assuming 
that in the 10 generations there have not been other carriers.  

We can quibble the numbers, but this is serious business I think we all 
agree.  This is where the BYB and the working dog breeders in many cases 
really loose it and could be a source of major problems for the breed.

Joe