College of Veterinary Medicine

Veterinary Teaching Hospital

Important Announcement about Equine Herpes

EHV-1 Outbreak: USDA Releases Final Situation Report June 23, 2011


WSU reopens teaching hospital   June 13, 2011


Recent Publications/Links

See bottom of this page for additional resource links


Update May 31, 2011

WSU Veterinarians confirm postmortum equine herpes case


Update May 26, 2011

As of May 26, 2011, a total of 75 confirmed EHV-1 cases have been reported in 9 states (AZ, CA, CO, ID, NM, NV, OR, UT, WA). Of the 75 confirmed cases, 58 cases are horses that were at the Ogden, Utah event. There are 11 horses associated with this incident that are dead or have been euthanized; none are from Washington.

Washington's summary remains seven known EHV-1 positive horses and no deaths. By county Whitman has three positive cases, and Spokane, Chelan, Asotin, and Thurston counties have one each. The case in Asotin County was diagnosed at Washington State University's Veterinary Teaching Hospital.

Update May 25, 2011

WSU Veterinarians confirm third in-patient EHV-1 case 

Decontamination suggestions for EHV-1

To decontaminate yourself, we recommend that you take a shower, change clothes, and wash the clothes that you were wearing when you handled the "suspect" horse. 

These are the recommendations by the American Association of Equine Practitioners for decontamination of equipment and supplies that may have been in contact with horses who are shedding herpes virus:

  • Horse-specific equipment (feed tubs, water buckets, halters, etc.) should be clearly identified as belonging to an individual horse and is to be used only by that horse.
  • Shared equipment (lead shanks, lip chains, bits/bridles, twitches, dose syringes, thermometers, grooming supplies) should be cleaned of organic debris and disinfected between horses.
  • All equipment should be thoroughly scrubbed and cleaned with a detergent and water, rinsed, disinfected and followed by a final rinse. This should be done in an area with minimal foot and traffic flow that can be cleaned and disinfected after this procedure (preferably not in a grazing area, but on a solid surface close to a drain).
  • Cloth items (saddle cloths, towels, bandages, halter fleeces, rub rags) should be laundered and thoroughly dried between each use. (Disinfectant may be added to rinse water, but additional rinse cycle must be used to remove disinfectant residue.)
  • Equipment that cannot be effectively disinfected (sponges, brushes) should not be shared between horses. Multiple dose medications (oral pastes/ophthalmic ointments, etc.) should be labeled for use by a specific horse and not shared.
  • Ointments/topical medications should be removed from larger tubs and portioned into smaller containers for use on individual horses.


Update May 20, 2011

The WSU College of Veterinary Medicine confirmed two more horses with Equine Herpes Virus or EHV-1 on May 20.  Both horses are inpatients in the Veterinary Teaching Hospital.

The EHV-1 type is confirmed as the neurotropic form.

The discovery of two more infected horses at WSU means the restrictions for new, non-emergency horse or camelid patients coming to WSU’s Veterinary Teaching Hospital will be in place for a minimum of 21 more days. 

Emergency services are still available but owners must call ahead first to ensure the hospital can make special accommodations to protect any incoming animals.  The phone number is: 509-335-7073.

Update May 18, 2011

Washington saw its first EHV-1-positive case discharged from Washington State University's (WSU) Veterinary Teaching Hospital on May 13 (details below).  Today Debra C. Sellon, DVM, PhD, Dipl. ACVIM, a professor of equine medicine at WSU, reported that since the discharge all PCR diagnostic tests run on hospital patients have been negative, and the university hospital remains under quarantine.

Today (May 18) a second case of EHV-1 was confirmed. The horse presented with neurologic signs and was taken to Pilchuck Veterinary Hospital (PVH) in Snohomish. Attending veterinarian Wendy Mollat, DVM, Dipl. ACVIM, said in a press release issued by the hospital that upon presentation to PVH, "the horse was immediately admitted to our designated equine isolation facility and has not been allowed direct or indirect contact with our general equine population. The horse is clinically stable and will remain hospitalized until confirmed to be no longer shedding the virus."

A third case was reported today in the state of Washington but no details were reported.

May 14, 2011

The Washington State University Veterinary Teaching Hospital is entering a period of voluntary isolation for equine and camelid patients.  This is in response to a patient that was confirmed to be shedding Equine Herpes Virus type 1 (EHV-1).   In the past week there have been 2 confirmed cases of EHV-1 in Colorado in horses that competed at the National Cutting Horse Association Western National Championships in Ogden, Utah.   A horse admitted to the Washington State University Veterinary Teaching Hospital for evaluation of unrelated problems was found to have competed at the show.  Subsequent diagnostic testing confirmed that the horse was positive for EHV-1.   Due to the potential for spread of the virus, access to the VTH is currently restricted.  During this time, no new equine or camelid patients may be admitted to the hospital except for critical emergencies.  It is expected that the period of isolation will last at least 2 weeks.   There are currently no horses exhibiting signs of EHV-1 at WSU.    Equine Herpes Virus does not affect cattle, sheep, goats, pigs or birds, and the remainder of the VTH remains open.  There is no risk of transmission to people.

We are taking every precaution to ensure the health and well-being of animals.  We hope that the following information will be helpful .

Equine Herpes Virus is a common virus in equine populations worldwide.   There are several strains of the virus, with EHV-1 and EHV-4 being most often involved in clinical disease.   EHV-1 can cause respiratory disease, abortion and neurologic disease, while EHV-4 typically causes respiratory disease.   Neurologic disease, which is generally caused by specific strains of EHV-1, is called equine herpesvirus myeloencephalopathy (EHM).  

What are the common clinical signs of EHV?

Fever is one of the most common clinical signs and often precedes the development of other signs.  Respiratory signs include coughing and nasal discharge.  Abortions caused by EHV generally occur after 5 months of gestation.   Neurologic signs associated with EHM are highly variable, but often the hind end is most severely affected.   Horses with EHM may appear weak and incoordinated.  Urine dribbling and loss of tail tone may also be seen.   Severely affected horses may become unable to rise.   

It is important to remember that none of these signs are specific to EHV, and diagnostic testing is required to confirm EHV infection.  Also, many horses exposed to EHV never develop clinical signs.

How long is the virus shed once a horse is infected?

Shedding by the respiratory route typically lasts for 7-10 days, although occasionally it may persist longer.

How is EHV spread?

EHV  is transmitted primarily by aerosol and through direct and indirect contact.  Aerosol transmission occurs when infectious droplets are inhaled.  The source of infectious droplets is most often respiratory secretions.   In the case of abortions, virus may be present in the placenta, fetal membranes and fluid, and aborted fetuses. 

Direct horse-to-horse contact is a common route of transmission of the virus, but Indirect transmission is also important. This occurs when  infectious materials (nasal secretions, fluids from abortions, etc.) are carried between infected and non-infected horses by people or fomites (inanimate objects such as buckets, etc).

What should I do if my horse has been exposed to EHV?

If you suspect your horse has been exposed to EHV, contact your veterinarian.  In general exposed horses should be isolated and have their temperatures monitored twice daily for 10 days.  If an exposed horse develops a fever, diagnostic testing should be performed.  While there are several testing methods available, the most frequently recommended test is a PCR to detect the viral genetic material done on a nasal swab.

How do I get more information about EHV?

Last Edited: Jun 27, 2011 11:17 AM   

Veterinary Teaching Hospital PO Box 647060 , Washington State University, Pullman WA 99164-7060, 509-335-0711, Contact Us Safety Links