Central Asia, Australia, and Japan experienced large equine influenza virus (EIV) outbreaks in 2007 (1,2).
The most common clinical signs of EIV infection in equids are fever, lethargy, anorexia, nasal discharge, and a nonproductive dry cough (4).
A massive 1872 outbreak is considered the largest recorded EIV epizootic (12).
Major EIV outbreaks continued through the 1900s (Appendix Table, https://wwwnc.cdc.gov/EID/ article/25/6/16-1846-App1.pdf).
Outbreaks of EIV infections in horses occurred globally throughout the 2000s.
Authorities believe EIV escaped a quarantine station due to lax biosecurity protocols.
During 2011-2012, an outbreak of EIV Florida clade 1 began in Chile and spread to multiple countries in South America (4) through the movement of horses in the rodeo and thoroughbred racing industries.
In Mongolia, government records show 4 large EIV outbreaks with some of the highest known mortalities during 1974-1975, 1983-1984, 1993-1994, and 2007-2008 (21).
The primary focus of EIV prevention has been on domestic horses, but EIV is transmissible to all equids, including feral and wild herds, such as Przewalski's horses.
Cats experimentally infected with EIV demonstrated respiratory signs and virus shedding with transmission to other cats (29).
In Australia, in late 2007, an outbreak of equine influenza virus (EIV) infection occurred in horses.
Researchers in Japan have described transmission of EIV from 3 experimentally infected horses to 3 dogs individually housed with each horse (6).