Fainting Goats, No Kidding!

If you don’t believe me, take a quick look at this video.

Selective breeding can produce humorous results, but studies of these genetic mutants can further veterinary knowledge. The Myotonic, or ‘fainting’ goats’ most characteristic feature is the fact that they display a autosomal dominant, genetic condition called myotonia congenita. When they become frightened or excited, it causes the muscles in their legs to contract: they become stiff. There is a lag of about 10-15 seconds before their muscles relax and they are again able to move. Often, this stiffening of the leg muscles causes the goat to fall over, hence earning them the name ‘fainting goats.’

To allow normal muscle use, the muscle cell rapidly changes its membrane’s permeability to certain ions, creating spikes of electrical discharge, allowing it to contract. Myotonic goats however have a mutated form of the gene CLCN-1 that encodes for the permeability of chloride. It was found that this gene’s output differed between myotonic and normal goats only by one amino acid: proline is substituted in the Myotonic goats for alanine. This involves the change of one nucleotide base pair in the DNA sequence: codon CCC instead of codon GCC; affecting the gene’s abilty to function normally.

While such a trait could be seen merely as entertaining, the condition actually enhances muscle development. The determination of the genetic code responsible has allowed scientists to look into its use in other production animals, and to further understand the condition which can occur naturally in other animals including the Chow Chow dogs.

Emily Stevens – 41440999

Further information:
The International Fainting Goat Association [Click here]
Wikipedia: Fainting Goat [Click here]
Tennessee Fainting Goats [Click here]

Primary Reference:
Beck, C. L., Fahilke, C., George Jr, A. L. 1996. Molecular basis for decreased muscle chloride conductance in the myotonic goat. October Vol. 93, pp. 11248-11252 [Click here]

Secondary References:
Myotonia Congenital, Autosomal Dominant [Click here]
All Creatures, One Medicine [Click here]
Mytotonic, The breed or Displaying Myotonia? [Click here]