Conference Call Update on EHV-1 (Neurological Herpes/Rhino)
May 19, 2011
EHV-I virus situation in Alberta
A large group of equine veterinarians, provincial veterinarians and the Alberta Veterinary Medical Association had a conference call this morning regarding this issue. We reviewed the outstanding cases at this time and they are as follows:
• There is still only one confirmed case of a horse infected with the herpes virus in Alberta, that has showed neurological signs.  It was diagnosed on May 1, 2011 and was isolated at that time. This horse did not attend the Utah Cutting show but was in direct contact with several horses that did attend the show before they left Canada. This horse has been under veterinary care and has totally recovered. The origin of the source of infection for this horse remains unknown.
• As of May 18, 2011 there was one yearling tested positive for the neurological strain of the EHV-1 herpes virus but 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 isolated, being treated and is in no danger as this time.

• As of May 18, 2011 there is one additional horse that was in Utah, that also has tested positive for the neurological strain of the herpes virus.  This horse is only showing mild transitory respiratory disease, is in isolation, under treatment and also in no danger.
• There are tests pending on 6-8 other horses, which have attended the Utah show.  All are showing no clinically signs of the disease except for a mild fever in two of them. We expect some of these horses to have a positive test and have taken this into account on our comments below. [Post Scrip: results of 5 of these horses have come back by this evening, May 19, 2 were reported positive for the neurological virus but none are showing any further clinical signs]
• There are 3 cases being treated in BC in horses that attended the Utah show, one of which showed neurological signs but are all responding to treatment at this time.

 

Therefore, at this time, there have been no horses affected in the province of Alberta or BC 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.   Many other equine activities have also been cancelled for the next few days.
• All of the participants attending the Utah show have been notified and asked to keep their horses isolated until the danger of them transmitting the virus is over.
• 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.

It is the opinion of this group of veterinarians the risk associated with attending a competition or event is very low at this time. This is due to the fact that only one horse has been affected with the neurological form in Alberta and currently there has been no “second wave” of infection. We will be monitoring this situation closely and will update this position if there is any significant change.  If we are going to see more cases, they should appear within the next 7 to 10 days