Spider Lamb Syndrome

 

Leah Scholz

 

           

 

Background

          Spider Lamb Syndrome is also known as Hereditary Chondrodysplasia.  It is a genetically acquired disorder that results in deformities of the skeleton in young lambs.  This disorder is a recessive genetic disorder.  This means that lambs that have this disorder receive one recessive gene from both parents. 

This disorder is found predominantly in blackface lambs.  General figures show that 75% of the lambs that have it are of the Suffolk breed, and 25% are of the Hampshire breed. 

 

History of the Disorder

          Spider Lamb Syndrome is thought to have originated by a genetic mutation in the Suffolk breed in the late 1960ís.  However, this disorder did not start to become a widespread problem until the early and middle 1980ís.

          Spider Lamb Syndrome involves the improper formation of bone.  In a normal lamb, cartilage forms and minerals are put down at the end of the cartilage to form calcified bone.  This process is altered in a spider lamb sheep.  Some cartilage is ossified into bone while other cartilage in the same area is not. 

The deformities that result includes long and bent legs, curved and twisted spines, flattened rib cages, and abnormally long necks.  The most commonly observed deformity is splayed legs.  This involves the portion of the legs below the knee jutting outward at a 30 to 45 degree angle.  The legs resemble spider legs, and that is how the disorder acquired its name. 

Lambs with the disorder may not show visible signs at birth, but deformities can be seen 4 to 6 weeks after birth.  These deformities make it hard for the lambs to nurse.  Therefore, many of these lambs do not survive.

 

 

 

 

References

 

http://ag.ansc.purdue.edu/sheep/ansc442/Semprojs/defects/genetic_defects.htm

http://www.breedersworld.com/sheep/articles/spider.html

http://www.cvmbs.colostate.edu/dlab/webdocs/ext_vet/cleon13

 

 

             


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