[Jacob-list] Split Upper Eyelid Defect (SUED)

[Jacobflock at aol.com]

In a message dated 4/2/2003 11:49:30 AM Central Standard Time, 
shepherdofspots at yahoo.com writes:

> re split eyelid - it is genetic, but I believe it's
> the combination of BOTH ewe and ram that causes it.
> That ewe w/another ram might be fine. 
> 
> 

Split Upper Eyelid Defect (SUED) is a congenital defect associated with 
polycerates including Jacobs.  The defect APPEARS to be an autosomal 
recessive.  That means both rams and ewes can be carriers.  A "normal" eyelid 
ram or ewe that is a carrier  bred to a "normal" carrier can produce 1 SUED 
progeny, 1 normal eyelid and 2 carriers which will look "normal".

In North America we use the terms SUED "type" for Jacobs.  In Great Britain, 
the term "fault" is use for the Jacob as well as other polycerates.  A vet 
may use a type or grade of hip dysplacia to describe a dog's condition.  
However, hip dysplacia is a congenital defect.  It should be bred away from 
and can be minimized by observing all offspring.  Selective breeding 
processes that do not account for all the progeny, lack of close observation, 
etc., are all factors that help the fault move forward.  I seem to recall a 
situation a few years ago wherein after accounting for all the progeny, about 
50% of the lambs from "normal" eyes had SUED from 2 thru 4. 

The "type" or grade (2,3,4) is not recessive.  Some have suggested a type 2 
to a type 2 produces a type 2.  This is not a correct characterization of the 
defect.  In fact a type 2 ram over type 1 and 2 ewes have produced 50% SUED 
lambs with types 2 thru 4. 

Fred Horak

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