Subclinical infections with equine herpesvirus 2 and 5 in Swedish trotters; the occurrence and its association with poor performance

The equine herpesviruses 2 and 5 (EHV-2 and -5), viruses that persistently infect horses and that can be reactivated with stress or
illness, were initially thought as harmless. Recently however there is growing evidence that those can cause low-grade respiratory
disease or even severe lung damage. Since diagnosing mild diseases are challenging, they often go undetected and can be a source of
poor athletic performance.
There are preliminary results from the ongoing project Betydelsen av lågvirulenta virus och subkliniska luftvägsinfektioner hos
svenska travhästar suggest that EHV-2 and -5 may have an association with poor performance in Swedish trotters. However, this
needs to be further evaluated and the suggested study intend to investigate if there is an association between those viruses and
respiratory disease or poor performance. The project also aims to evaluate the diagnostic method, before it can be used by the equine
industry.