Detection of clade 2 equine influenza virus in an adult horse recently imported to the USA

Summary A 4‐year‐old W armblood mare presented to the W illiam R . P ritchard V eterinary M edical T eaching H ospital, S chool of V eterinary M edicine, U niversity of C alifornia at D avis with bilateral mucoid nasal discharge and pyrexia. The mare had recently been imported from G ermany, arriving at a quarantine holding facility 72 h prior to presentation. Based on clinical presentation and culture results of tracheal fluid, the mare was diagnosed with bacterial bronchopneumonia secondary to equine influenza. The equine influenza virus ( EIV ) identified in the imported mare displayed 99.1% nucleotide homology of the HA1 gene to the prototype F lorida sublineage clade 2 isolate A /equine/ R ichmond/1/2007 ( H3N8 ). This case illustrates the risk of introducing a clade 2 EIV in N orth A merica.