[Jacob-list] split eye-lids

[Jacobflock at aol.com]

In a message dated 10/8/02 4:16:51 PM Central Daylight Time, 
rbskarin at webtv.net writes:


> I want information on split eyelids. What happens if they are in stage
> 3? 
> Barb
> 

You ask a very interesting question ... "if they are in stage 3" ... implying 
that there is a progression of SUED from "stage 2" to "stage 4".  

The grades of the SUED defect for the Jacob were established by the Jacob 
Sheep Society in England based on the condition observed in several British 
multi-horned breeds.  The eye grade was as follows: TYPE 1 - A normal round 
eyelid, TYPE 2 - and almond shaped eyelid, FAULT 1 - a well defined and 
obvious break in the yelid, FAULT 2 - Tuft of hair or waon th edge of the 
eyelid or eyelashes growing under the eyelid, FAULT 3 - a full scale split  
extending to the top of the eyelid.   

The Jacob breeders in North America do not use the word "Fault" as a 
descriptor but the word "Type", and classify the SUED defect as Type 2 
-slight, Type 3 - split that is often tufted and Type 3 - Severe with a 
cloudy or opaque eye.  A photo table of SUED defects by Type was prepared by 
Colorado State University for their teaching program and Peter Spellmeyer has 
collateral information on SUED from his multi horn skull observations of 
notches in the occipital orbit.  Inquiries have and are being made to find a 
veterinary opthamologist to offer further insight into this defect.  Pictures 
are also available in I Painter's book "Jacobs in North America".

The "type" is most often determined at birth except in those few cases when a 
field examination is done and the condition recorded at the time of the field 
examination.  The SUED defect might be graded as Type 2 ("mild" or slight 
notch) at birth but I am unaware of any longitudinal observations as to SUED 
progressing to Type 3 or 4; or Type 3 progressing to Type 4 as you describe 
as a "stage".  

A "stage 3" will depend on where you live (Britain or North America), your 
powers of observation and type classification and the age of the sheep (can 
it be progressive?).

SUED is associated with multiple horns and is described as a "recessive" 
trait but it is unclear if it is a simple recessive.  It is a defect and 
should be avoided in a breeding program.  The defect is recessive, the grade 
is not recessive.  Some have suggested that a Type 2 bred to a Type 2 
produces Type 2.  This suggestion is not a correct characterization of the 
defect.   Reports of a Type 2 SUED ram over Type 1 and Type 2 ewes have 
produced 25% to 50% SUED lambs with Types 2 through 4.  The use of a "Stage 
3" for breeding is a risk for affected lambs and carrier lambs. 

I hope this is helpful.  Fred Horak

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