CIDs

[Linda_Merims@ne.3com.com]

Lif Strand said:

>Joan - it's too bad the stud was gelded if he was a high quality
>breeding animal otherwise - there is no worry about CID if everyone is
>honest and open about having carrier animals.  It's not as if it *has*
>to be fatal (if only one parent is a carrier), and after all, it's not
>actually a disease that is contagious!
>
>All breeding animals carry some assortment of undesirable recessive
>genes (and some undesirable dominants as well!).  As long as breeders
>are aware of them, breeders just avoid crossing to animals with them -
>or, picks an animal to cross to that has genes that will counter the
>undesired ones.  For instance, if a breeder  doesn't want "high white"...
>
>Nobody thinks twice about breeding this way, so it seems to me
>it follows that  if everyone was open about the presence of recessive
>CID in their breeding animal, it wouldn't be a big deal at all.



My breed is Morgans, not Arabs, but I have some dim
recollection that not everybody in the Arab world shared
Lif's outlook.  In fact, I kind of thought the discovery of
CIDs in Arabs created a huge storm of controversy and a
knock-down, drag-out, blood all-over-the-place fight within
the breed over whether CIDs carriers should be allowed to be
registered at all.  It was a lot like the Impressive Syndrome
problem in Quarter Horses.

Are Arabs required to be CIDs tested before they can be
registered?  With a positive or negative indication on the
papers?

The problem is that going "laissez-faire" with CIDs, even
with testing, still means that the recessive spreads
much more widely through the population and there become
fewer and fewer horses that you can match together.  As
somebody interested in heirloom mare lines in Morgans, for
instance, one would hate to get in to the position where
the only living descendants of a "clean" mare line now
have the CIDs gene because the last daughter was crossed
with a CIDs stallion who happened to fullfill the 50%
chance to pass on the gene.

A human worst-case example with similar inheritance
properties and similar ultimately fatal results is
sicle cell anemia.

What is the history of CIDs in Arabs?  Did it start out
in one horse or one breeder's herd like Impressive Syndrome,
or was it always kind of endemic and spread evenly
throughout the population?  How widespread is the presence
of the gene now?  Is its incidence being tracked?


Linda B. Merims
lbm@ici.net
Linda_Merims@ne.3com.com
Massachusetts, USA




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