BIOSECURITY GUIDELINES FOR EQUINE HERPES VIRUS TYPE 1 (EHV-1)

Background: The transmission of EHV-1 occurs primarily from infected horses to uninfected horses through the shedding of virus in respiratory secretions through coughing, snorting or sneezing. (Note: It is not as easily shed by this route as is Equine Influenza virus. Influenza viruses are much more contagious). Mares who have aborted or whose foals have died can also transmit the virus via the respiratory route. Aborted fetuses, fetal membranes and/or fluids can be significant sources of infection. Infected foals are highly contagious and can transmit the disease to other horses via the respiratory route and by shedding into the environment. Shedding by the respiratory route typically lasts for 7-10 days but can persist for perhaps as long as 21-28 days.

Environmental transmission plays a minor role in the maintenance of the virus in the horse population since environmental persistence of EHV-1 is short, estimated to be no more than 35 days under ideal conditions and probably less than seven days under ideal conditions. In general, viruses survive well under cold, damp, dark conditions and are inactivated by heat, light and drying. Inanimate objects such as feed and water buckets, grooming tools, tack, contaminated clothing and footwear can be sources of spread.

With these facts in mind, the following biosecurity procedures are recommended:

1)                          Thorough cleaning to remove all organic matter and dirt should always precede disinfection.  Disinfectants should always be mixed at the recommended concentrations and not by the “glug” method. If it says one tablespoon per gallon, it means one tablespoon per gallon and not two.

2)                          An excellent, cheap and readily available disinfectant is five tablespoons of household bleach per one gallon of water. This can be then used to spray or dip cleaned surfaces, tools, footwear, etc.

3)                          Changing coveralls and cleaning and disinfecting boots when moving between farms just makes common sense and can help minimize the risk of spreading all types of diseases.

4)                          Isolation of new horses entering a facility for 14-28 days, if possible, is always a good idea. Isolating new animals in a separate barn would be ideal but if this is not possible, avoid direct contact with resident horses for the isolation period. Always handle and feed healthy horses first and then handle the suspect or isolated horses.

5)                          Vaccination of new animals before entering a facility should be done at least 14 days prior. Owners should consult with their veterinarian on recommendations for the type and interval for vaccination.

6)                          Signs can be posted at barn entrances to discourage unwanted visitors, indicating that the barn is a biosecure area and that visitors should check with the owner before entering.

7)                          Temperatures of isolated animals can be monitored twice daily to give advance warning of a possible problem.

For more information, please consult your veterinarian and the Maine Department of Agriculture at website: http://www.maine.gov/agriculture/ahi/diseases/index.html