Hysterical videos of these fainting goats can be found on YouTube, always giving us a good laugh. In the videos, we see that when these goats are startled, instead of being able to run away, they seem to become rigid and fall over. So what is the cause behind this fainting behavior?
These fainting goats, otherwise known as myotonic goats, are actually domestic goats (Capra aegagrus hircus) with a hereditary genetic disorder called myotonia congenita. An article by Carol Beck et al. (1996) describes this as:
“A condition characterized by delayed relaxation of muscle secondary to sarcolemmal hyperexcitability, are caused by diminished chloride conductance in the muscle cell membrane.”
To put it in simpler terms, this is a condition where the muscles of the goat contract when it is startled. Although this is painless, it causes the goat to fall over on its side. The name is a little misleading, however, since the goat does not actually faints, and remains conscious during such attacks. Such prolonged muscles contraction can last from a few seconds to a more than a minute before the muscles gradually relax and voluntary movement returns. This falling over is seen more commonly in young goats whereas older goats usually stay stiff with legs spread open or run about awkwardly with their stiff legs. This is because they learn over time and they are more prepared for what is to happen when they feel their muscles tensed up.
This condition makes the goats vulnerable to predators, and it is said that these goats have a historical purpose. Shepherds usually had these goats together with their sheep to save the sheep from predators. For example, when a wolf attacks, the goats fall and become the easy prey, allowing the sheep to make an escape. Fortunately, fainting goats are no longer used for this purpose.
This fainting behaviour has also been found in cats, although cases of cats with this condition are more rare. Read more about fainting kittens at: “‘Fainting goat’ kittens could be unique in UK,” by Alex Emery. BBC News. 30 October 2010. URL: http://www.bbc.co.uk/news/uk-11653848 (accessed on 8 April 2013)
Beck Carol L., Fahlke C., George Alfred L. Jr, 1996. Molecular basis for decreased muscle chloride conductance in the myotonic goat. Proceedings of the National Academy of Sciences of the United States of America, 93(20): 11248-11252. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC38315/pdf/pnas01524-0721.pdf
Clark, Sam L. M.D., Luton, Frank H. M.D., Cutler, Jessie T. Ph.D., 1939. A Form of Congenital Myotonia in Goats. The Journal of Nervous and Mental Disease, 90(3): 297-309. http://journals.lww.com.libproxy1.nus.edu.sg/jonmd/Citation/1939/09000/A_Form_of_Congenital_Myotonia_in_Goats.1.aspx
“Fainting Goat” from Wikipedia, 19 March 2013. URL: http://en.wikipedia.org/wiki/Fainting_goat (accessed on 8 April 2013)
“Fainting Goat Facts” from Sutcliffes Goldens & Goats. URL: http://sutcliffesgoldens.weebly.com/fainting-goats.html (accessed on 8 April 2013)
“Fainting Goat experiencing Myotonia (fainting).” by Wikipedia user “Redleg”. Wikepedia, 12 July, 2006. URL: http://en.wikipedia.org/wiki/File:Fainted.jpg