Ovine_chondrodysplasia
Spider lamb syndrome
Genetic disorder of sheep
Spider lamb syndrome, also known as spider syndrome[1] and more formally as ovine hereditary chondrodysplasia,[2] is a homozygous recessive disorder affecting the growth of cartilage and bone in sheep. The name derives from the limbs of afflicted animals being thin, elongated, and "spider-like".[3]
It is a semilethal trait,[4] which is thought to have been first observed in the 1970s,[5] and is most common in sheep of the Suffolk and Hampshire breeds.[6] These are both black-faced breeds of sheep; the syndrome has never been detected in white-faced breeds.[7]
The syndrome was an economically significant issue for sheep breeders in the 1980s, [8] but with strict testing and breeding programs it has become less common.[8]
The mutation which causes spider lamb syndrome is found on ovine chromosome 6,[9] and involves the inactivation of fibroblast growth factor receptor 3.[10] It has been compared to dwarfism in beef cattle.[7]
Afflicted animals may be visibly deformed at birth and unable to stand, or seemingly normal for the first 4 to 6 weeks of their lives.[4]