Update on EHV-1 / June 12, 2011

Another Two Horses Test Positive for Virus

Sun, 06/12/2011 – 23:58

By Dana Cole


SIERRA VISTA — Two more Arizona horses have tested positive for equine herpes virus, or EHV-1, one with the EHM or neurological variant, according to a local equine veterinarian.

Dusti Prentice, whose practice is Southern Arizona Equine, sent an email to her clients on Saturday advising them of Arizona’s latest two confirmed cases. The virus was first reported at a cutting horse competition in Ogden, Utah, in late April and has spread to other states from a few horses that contracted it at that event. The spread of the virus has been somewhat contained through coordinated quarantine efforts and widespread event cancellations throughout western states.

“The state and USDA vets are not releasing the location of the positive cases,” Prentice said. “This is the second confirmed EHM case in Arizona.”

The first confirmed EHM case occurred in a horse from the Prescott area that was exposed at the Utah event.

The National Cutting Horse Association notified state animal health officials of horses from their state that were entered in the event and may have been exposed to the virus. In turn, state animal health
officials contacted the owners of the potentially exposed horses. Exposed horses have been isolated and monitored for clinical signs of EHV-1.

While the number of confirmed EHV-1 cases across western states continues to drop, Prentice said the decrease could be because some people are reluctant to test due to the cost. The United States Department of Agriculture posts weekly reports on its website, http://www.aphis.usda.gov/vs/nahss/equine/ehv, in order to keep concerned horse owners updated on the number of cases and which states are experiencing outbreaks. Those weekly reports are expected to continue for another six to eight weeks.

“The USDA did an excellent job of limiting the spread of the virus through identifying and quarantining the affected or exposed horses,” Prentice said.

While it seems the outbreak is on the decline, intermittent cases across the western United States continue to be reported, she added. Despite the occurrences, horse competitions and events are beginning to be rescheduled, some as early as mid to late June, Prentice said.

When traveling with horses, Prentice is urging horse owners to observe such bio-security protocols as refraining from sharing water or feed buckets, tack or brushes between horses. In addition, nose-to-nose contact between horses should be avoided. Wash hands often or use sanitizers when handling horses from different stables. Horses should be monitored for signs of illness, to include decreased appetite, fever of 101 or higher, depressed attitude, uncoordinated movements or nasal discharge.

For those who plan to travel to other states, a health certificate may be required when transporting horses across state lines. It’s best to check with state veterinarians to see what restrictions or requirements are in place.

All those with questions about the virus, or with concerns about their own horses, should contact their veterinarian.

Prentice can be reached at 520-678-5566 or by going to dr.prentice@sazequine.com.


The following information is the most current EHV-1 incidence update provided by the United States Department Agriculture.

Primary exposed horses — exposed at the Ogden, Utah, event: 32 EHV-1 cases; 26 EHM or neurologic cases; and 10 dead or euthanized cases.

Secondary and tertiary exposed horses: 23 EHV-1 cases; seven EHM cases; and two dead or euthanized cases.

To date, 19 states are reporting horses with primary exposure to EHV-1 after participating in the Utah event, for a total 421 exposed animals. Of that number, 40 are EHV-1 suspect cases, 32 are EHV-1 confirmed cases, six are suspect EHM or neurological cases, 26 are EHM confirmed cases and 10 horses are dead or euthanized.

In Arizona: There have been 33 primary exposed horses (horses exposed at the Utah event), with four suspect cases of EHV-1; two confirmed cases of EHV-1; two suspect cases of the EHM or neurological variant; one confirmed case of EHM; and one dead or euthanized cases.

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