Neurotropic Equine Herpes Virus -1 Update

Published: May 21, 2011 12:00 am EDT

Equine Canada’s Health and Welfare Committee is notifying horse owners that Neurotropic Equine Herpes Virus-1 (nEHV-1) has been reported in horses in the United States, with confirmed cases in Alberta (1) and suspected cases British Columbia (3)

. This is the neurological strain of Equine Herpes Virus 1 (EHV 1). Outbreaks of nEHV-1 are contagious and have a high risk of mortality.

It is believed the initial cases were in horses attending a cutting horse show in Ogden, Utah, held April 29 to May 8, 2011, and that horses exposed to the virus at this competition have played a role in reported cases elsewhere.

The horse in Alberta did not attend the cutting horse competition. The horses in British Columbia, which all reside on the same farm, did. Quarantine and biosecurity procedures have been established and no secondary cases have been reported at this time, on this farm.

Please note that the nEHV-1 cases reported in British Columbia have not been confirmed by laboratory testing, but through clinical diagnosis. The three British Columbia horses that returned from the Odgen show developed neurological disease and are being treated intensively as if they had nEHV-1. Strict biosecurity procedures have been put in place to prevent spread of this disease from this farm.

Update from Alberta

There is one confirmed nEHV-1 case, which showed neurologic signs on May 1, 2011 and was isolated at that time. This horse did not attend the Utah show but was in direct contact with the horses attending the above stated show before they left Canada. This horse has been under veterinary care and is recovering very well and is in no danger. The origin of the source of contact for this horse remains unknown.

• As of May 18, 2011 there is one yearling confirmed positive for EHV-1, which showed only respiratory signs of the disease similar to normal influenza infections. This horse was in direct contact with tack from the horses returning from Utah. This horse is under treatment and isolation and is in no danger as this time.

• As of May 18, 2011 there is an additional confirmed positive case of a horse returning from Utah, which showed a mild transitory respiratory disease. This horse is under isolation and treatment and is in no danger.

• There are six–eight tests pending on horses similar to the above horse, which have attended the Utah show and have experienced mild respiratory disease. We expect some of these horses to have a positive test and have taken this into account on our comments below.

Therefore, at this time, there have been no horses affected in the province of Alberta or British Columbia that were not either at the Utah show or in direct contact with these horses, either before or after their return. The incubation period for this disease can be as long as 21 days but normally symptoms show within the first 10-14 days. Presently, we are within the 10-14 day timeframe.

Measures that have been taken

• Competitions involving the horses directly affected by the Utah Show have been cancelled by the Cutting Horse Association until further notice.

• All of the participants attending the Utah show have been notified and asked to isolate their horses.

• The Chief Provincial Veterinarian is gathering all information, monitoring the disease and is looking into the epidemiology of EHV-1 in Alberta at this time.

Ongoing recommendations

• All horse owners have been asked to carry out normal biosecurity protocols, which can be found on many websites, including that of the Alberta Veterinary Medical Association.

• Any horse owner who has potentially been in contact with this group of horses should monitor the temperature of their horses twice daily for 14-21 days post exposure and discuss any abnormalities with their veterinarian.

• The protection afforded by vaccination is debatable and we recommend that horse owners discuss it with their veterinarian, as every horse is unique and requires a different vaccination protocol.

The following is a statement from the Canadian Food Inspection Agency (CFIA)

Equine Herpes Virus (EHV) is a disease present in Canada and is not a federally controlled disease. Subsequently, in accordance with international guidelines, CFIA has no authority for requesting certification related to this disease from the United States Department of Agriculture when importing horses from the United States (U.S.). Import conditions for all horses entering Canada from the U.S. will not be changed in relation to the recent reports of EHV cases in the U.S.
However, as always, imported horses need to comply with all current Canadian import conditions. In addition, arrival of unwell horses at the border can affect the import process.

Equine Canada is working with the offices of Canada’s chief veterinarians to monitor the situation and keep members abreast of developments. They will post new information and status updates regarding nEHV-1 on their website at

Outbreak control of nEHV-1 is dependent on proper biosecurity or containment strategies. Owners are encouraged to speak with their veterinarian if they have additional concerns or questions.

(Equine Canada)

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