The Latest on the Midwest EHV-1 Outbreak: Information from North Dakota, Iowa, Minnesota and Wisconsin

April 17th, 2014 8:54 AM | No Comments


North Dakota

There have been three cases of EHV-1 confirmed in North Dakota since the beginning of the year.  All three cases are in Burleigh County, North Dakota in the Bismarck Area. The first two cases are from a closed herd, meaning no horses in or out for the last two months. The affected horses have now been re-tested, and were found to be negative.

The third case is a local Barrel horse, which has been reported to be in a competition the week before coming ill which apparently involved some Minnesota horses.  However, the good news is we are now 11 days from this horse being tested positive and no new cases have been reported. EHV-1 has an incubation period of 2-3 weeks.

ND Case 1 January 2014 on a closed herd
ND Case 2 February 2014 same closed herd
ND Case 3 April 5 2014 barrel horse


EHV1 case map

A map depicting cases from the tri-state area. Click the map to see a larger image.

Reported 4/16- The suspected case in Pierce County WI had been tested for EHV-1 due to a high fever. The test results were negative for EHV-1, and were found positive for EHV-4 (which like the common cold). This is a common diagnosis, and of little concern in the face of this outbreak of EHV-1.

As of April 14, there are no new confirmed cases or new neurologic cases that vets know of.

Summary to date

Case State County Date  (Positive neurologic symptoms and positive tests)

Case 0 WI St Croix County high suspicion euthanized 2/15/2014
Case 1 MN Chisago Euthanized EHV-1 positive 3/8/2014
Case 2 MN Chisago Recovering EHV-1 positive 3/8/2014
Case 3 MN Dakota Euthanized EHV-1 positive 3/18/2014
Case 4 WI Polk Recovering EHV-1 positive3/20/2014
Case 5 MN Hennepin Recovering EHV-1 positive 3/21/2014
Case 6 MN Freeborn Recovering Test positive 3/26/2014
Case 7 MN Wright Test positive 3/26/2014
Case 8 Iowa and MN Freeborn and Hennepin Positive 3/26/2014
Case 9 MN Wright county Test positive 3/29/2014
Case 10 WI St Croix County Recovering Test positive 4/4/2014

*Case 1+2 are on the same farm
*Case 0 + 10 are on the same farm

Out of these ten cases, MN has 7/10 WI has 2/10 Iowa has 1/10, with 7/10 of the affected being Barrel or Game horses. 8/10 of these cases have been in the northern suburbs, north of Hwy 94/394/12.

Case X WI Burnett Euthanized 3/20/2014 test negative
Case X MN Isanti 4/7/2014 test negative

Positive Neurological signs: Hind leg ataxia, Bladder dysfunction,
Positive Respiratory signs: Coughing, nasal discharge
Positive lab tests : PCR nasal swab, PCR blood, blood titer
Positive case: positive neurological signs and positive lab tests

“No travel” guidelines are recommended 2-3 weeks from the last clinical case. Veterinarians have called for a 14 day travel restriction for horses in Minnesota, meaning (pending no new cases), the travel restrictions will be lifted 4/22.

The Minnesota Board of Animal Health voted to make Equine Herpesvirus Myeloencephalopathy (meaning horses with neurologic symptoms attributable to EHV-1) a reportable disease in Minnesota, regardless of what strain of EHV-1 causes it. Previously, only the more aggressive “neuropathogenic” EHV-1 strain was reportable. Representatives from the University of Minnesota, area private practice vets, the Minnesota Racing Commission and local trainers gave great presentations to the Board, who granted the request. This means that in the future, the Board will be able to be much more involved in tracking the epidemiology of outbreaks, and possibly instituting formal quarantines for affected premises.

This will hopefully result in a more unified effort, a freer flow of information and more specific recommendations for travel, should this type of outbreak occur again.

“This was a great example of the equine veterinary community coming together to create meaningful change for our horse owners. While these changes may not make a lot of difference during the current outbreak, the Board has still agreed to look more closely into the current cases and work toward ‘connecting the dots,’ which will give us valuable information going forward” –Cleary Lake Veterinary Hospital.

Minnesota Horse Expo

The following is a statement from the Minnesota Horse Council and Minnesota Horse Expo regarding the decisions that have been made for the event:

15 April 2014- To Horse Exhibitors, Enthusiasts and Owners coming to the MN Horse Expo:
“As of April 8th there have been 10 confirmed cases of neurologic disease caused by Equine Herpes Virus-1 (EHV-1) in Minnesota, western Wisconsin and Iowa. The majority of the cases are in Minnesota. We support the two-week no travel ban to help control this outbreak. If there are no further confirmed cases with this outbreak, the travel ban would be lifted April 22nd.

We take your horse’s health very seriously. With this disease foremost on our minds, the Minnesota Horse Expo and Minnesota Horse Council made many difficult decisions regarding this year’s Expo. The decision to limit the number of horses coming to the Expo was not made in haste. We know that this would affect many that use the Expo to market their horses but we have put in place biosecurity procedures to protect any horse that comes to the Expo. We could not protect the number of horses that usually come to the Expo. We chose to limit the horses to entertainment, clinician and rodeo horses. All these horses will be kept isolated at the Expo and there will be controlled, limited public access.

All horses coming to the Minnesota Expo must be accompanied by a health certificate dated April 17 or later. All horses will be checked by Expo personnel before entering the Expo. Health certificates contain information on the origin of the horse, so we will know if horses come from the outbreak area and if necessary, these will be turned away at the gate.

The Minnesota Horse Expo is planning a great program, something for every horse enthusiast. We are adding Equine Herpes Virus education, so that every person that enters the Expo will learn about the transmission and prevention of this potentially devastating problem.

It is our goal, that Minnesota Horse people will lead the nation in responsibly handling equine disease outbreaks.

Tracy A. Turner, DVM, MS Glen Eaton President, Minnesota Horse Council President, Minnesota Horse Expo”

 For more information,  check out the links below:

Information has been posted at Stillwater Equine Veterinary Clinic, Cleary Lake Veterinary Hospital, and Anoka Equine Veterinary Services. We thank these veterinary clinics for keeping everyone up to date and informed of the latest in this EHV-1 outbreak. Please contact your vet if you have any concerns about your own horses, or questions about EHV-1.  


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