Study Reveals Equine Influenza Case Numbers on the Rise

For the third year in a row, the number of influenza cases in the United States is increasing, a recent study revealed.

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Equine influenza virus (EIV) is one of the leading respiratory diseases in the United States and, in recent years, the number of infected horses has been on the rise.

Since 2008, Merck Animal Health has collected more than 4,700 samples from horses presenting with signs of acute infectious upper respiratory disease and/or acute neurologic disease as part of an ongoing research program. The two leading diagnoses, based on samples submitted from horses of all disciplines and ages across the United States, have been equine herpesvirus-4 and EIV.

In an effort to protect horses against these two prevalent respiratory diseases, the United States Equestrian Federation (USEF) will implement a rule effective Dec. 1, 2015, mandating that all horses be current (within six months) on their EIV and equine herpesvirus vaccines prior to entering a USEF show

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