Cause of 2010 Icelandic Horse Epidemic Found

January 2013 Equus magazine talks about the cause of the 2010 Icelandic horse epidemic. In a period of 6 months in 2010, about half the horses in Iceland were affected with respiratory symptoms of nasal discharge and cough. The outbread was serious enough that export of horses was halted, and, if I remember correctly, Landsmot was cancelled that year.

Scientists working at the Animal Health Trust in the UK identified a bacterial strain of Streptococcus zooepidemicus (ST-209) as the culprit. Most likely a single horse farm (not identified in the article) was the source of this ST-209 strain. S. zooepidemicus "is rarely associated with large outbreaks of disease." (p. 13)