By Elizabeth Dean, DVM
EHV-1 is an acronym for Equine Herpes Virus type 1. Horses
that are affected by EHV-1 can have respiratory disease, abortion or neurologic
disease. Horses can also become infected with Equine Herpes Virus type 4, which
also causes respiratory disease and occasionally abortion. The most common
signs of respiratory disease due to EHV are an elevated rectal temperature,
coughing, and nasal discharge.
Equine Herpes Virus is spread from aerosol transmission most
commonly. This occurs when an affected horse coughs or snorts and aerosolizes
droplets which are inhaled by a nearby stable mate. Therefore, this disease is
transmitted during crowding situations such as a horse show. Horses that are
sick with EHV shed the virus for at least one week. However, recovered horses
have shed the virus longer; therefore once a horse is diagnosed with this
disease they should be isolated for 28 days. Environmental transmission plays a
minor role in infection because the virus does not last long outside of the
body. The virus lasts less than 1 week in a barn environment. Once a horse is
infected, they usually do not become ill for about 5 days. There are several
different ways to test for EHV. Please contact your veterinarian for assistance
if you believe your horse may be infected.
The current outbreak of Equine Herpes Virus is EHV-1 myeloencephalitis,
meaning this strain of EHV targets the brain of affected horses. Horses that
are infected with the neurologic form of EHV can have nasal discharge,
incoordination, hind end weakness, recumbency (laying down and unable to stand),
lethargy and fevers. This outbreak is related to a cutting horse show which
took place in Ogden, Utah at the end of April and beginning of May this year.
In total, 88 horses have been identified nationwide to be part of the outbreak.
Fifty-eight of those cases were horses that attended the horse show in Utah.
There have been 10 states involved in this outbreak, none of which are located
in the south or southeast part of the US.
The prognosis for horses that have the neurologic form of EHV
depends of the severity of clinical signs and if they have become recumbent.
There is no specific treatment for EHV but supportive care can help horses that
are affected. To date, there is no vaccine that has a label claim for
protection against the neurologic form of EHV-1.
If you suspect that your horse may have contracted EHV,
please contact your veterinarian for diagnosis and appropriate treatment. Separate
the horse from the rest of the herd to a place that is physically distant. Use different
supplies (wheelbarrow, pitchfork, water buckets) and wear coveralls when
handling the sick horse. To minimize transmission to other horses, instruct barn
workers to attend to the horses at the end of their shift. Stable help should
wear gloves when handling the horse and wash hands thoroughly with soap and
water when they exit the stall. Take the temperatures of all horses on the
property twice daily. If any animal has a rectal temperature of greater than
102 degrees Fahrenheit, isolate them and call your veterinarian. Healthy
animals that have been previously vaccinated for EHV should have their vaccine
boostered. Horses that have never been vaccinated will not have time to undergo
an effective vaccination series before the risk period if they are exposed to a
horse with EHV. Horses should be vaccinated and boostered now so that if they
become exposed, they may be protected.
Overall, the risk of horses in Florida contracting EHV-1 myeloencephalitis
is low. However, it is important to know the signs of illness to quickly
identify and halt an outbreak if one should occur.
For more information on Equine
herpes Virus you may contact lkuebelbeck@surgi-carecenter.com.
Additional information about EHV can also be found at www.aaep.org and further
updates on the EHV-1 outbreak can be found at http://www.aphis.usda.gov/vs/nahss/equine/ehv/.
This article was originally published in Horse & Pony magazine and is reprinted with their permission.