Thursday, November 2, 2006

Dwarfism in Texel Sheep

The best known inherited chondrodysplasia* of sheep is spider lamb syndrome in Suffolks and Hampshires. Affected lambs have abnormally long limbs and neck with angular limb formalities. A case report from New Zealand describes a different syndrome that was seen in a commercial flock of 1,100 ewes of mixed breeds in New Zealand. Over a 5 year period, up to 20 of 1,500 lambs born each year developed signs of dwarfism after birth, sometimes as early as 1 week of age or as late as 9 weeks.

The lambs showed reduced growth rate and a short neck and wide-based stance that often progressed to a deformity of the forelimbs and reluctance to walk. Some lambs died suddenly after exercise (being worked with sheep dogs), and these lambs had trachael collapse. Mildly-affected individuals had a short, blocky stature and some survived to breeding age. All of the affected lambs had Texel breeding on both sides of the pedigree, and some were twins to normal lambs.

This chondrodysplasia differs from those previously described in sheep and is considered to be a newly-recognized, recessively-inherited genetic disease of the Texel breed. This disease of sheep may provide a suitable model for studying various forms of therapy for human chondrodysplasias.

Source: New Zealand Veterinary Journal, 2005.

Chondrodysplasia - a hereditary skeletal disorder characterized by improper growth of the cartilage portion of the ribs.

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