EHV-2 And EHV-5: The Less Familiar Herpes Viruses

by | 05.23.2020 | 1:14pm

The most commonly-recognized equine herpesvirus strains for most readers are EHV-1 and EHV-4, which can cause respiratory distress, abortion and neurologic disease. Recent research suggests there are two strains that are often overlooked, though they are prevalent in the equine population and have been associated with multiple diseases: EHV-2 and EHV-5. A 2018 peer-reviewed study tested 167 horses that had been imported to the United States, many from Europe.

The study found:

  • 52 percent of the horses were shedding at least one herpesvirus
  • EHV-5 and EHV-2 were more prevalent than EHV-1 and EHV-4
  • EHV-5 was found in 40.76 percent of the horses
  • EHV-2 was found in 28.7 percent of the horses
  • 1.2 percent of the horses were positive for EHV-1
  • 3 percent of the horses had EHV-4
  • Horses that tested positive for any EHV strain did not necessarily show signs of illness, including nasal discharge, rapid breathing or fever

EHV-2 is believed to be present in nearly every young horse by the time it reaches four months of age; it can cause a sore throat and swelling of the lymph nodes, as well as a runny nose and fever. In older horses, EHV-2 may be associated with ocular disease, inflamed corneas and poor performance.

EHV-5 has been found to be quite prevalent in the equine population, though oftentimes the horses are asymptomatic. Horses that show signs of EHV-5 may have a lung disease called equine multinodular pulmonary fibrosis (EMPF), which causes signs of equine asthma. Horses with EMPF may lose weight, breathe rapidly and have a rapid heart rate. Not all horses with EHV-5 will develop EMPF.

Read more at DVM360.

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