You Oughta\’ Know About EHV-1

We\’re all concerned about the EHV-1 virus – the virus which presented at the April 29-May 8 Ogden, Utah, National Cutting Horse Association Western National Championships. Multiple horses from this competition began to show signs of the disease after the competition, including horses from Alberta, British Columbia, and nine states including California, Arizona, Colorado and Washington.

We\’ve touched base with a number of veterinarians and equine health officials on the subject throughout yesterday and this morning. We are reporting here, only confirmed information from veterinary clinics, the University of Calgary Faculty of Veterinary Medicine, and the Western College of Veterinary Medicine.

In Saskatchewan:

Dale Godson, of Prairie Diagnostic Services at the Western College of Veterinary Medicine confirmed he has received samples, 3 of which were positive for EHV-1.

He stated, “This is a sporadic disease, we have a few infections every year, that is not uncommon. Sometimes it is more infectious, which can become an outbreak. I cannot say that this is what I am seeing, since we have only had three samples. We also don\’t know the contact between the animals from the samples. Herpes viruses also case latent infection, which can be reactivated in the animal over time.”

Dr. Perry Jule, from the northern district of Saskatchewan said she has no cases that she is aware of in her district.
Moose Jaw Animal Clinic has had no cases. Also, Sherwood Animal Clinic in Regina has no cases.
In addition, I just minutes ago received this press release from the Saskatchewan Horse Federation:
“To date, there have been no reported cases of EHV-1 in Saskatchewan originating from the National Cutting Show in Utah.

“In Saskatchewan in March /April 2011, Prairie Diagnostic Services reported three cases of EHV-1. In 2010, there were three positive cases detected in Saskatchewan. There has not been a demonstrable increase in illness due to EHV-1 in Saskatchewan in 2011.

“We caution against mass hysteria in response to the many reports of EHV-1 that are circulating in our province and in Alberta as well. Alberta has, to date, only one confirmed case of EHV-1 with neurological signs, that being a horse that was at the National Cutting Horse Show in Utah at the end of April/beginning of May. Several additional cases have been reported in Idaho and Colorado.

“We also continue to caution all horse owners to always observe strict biosecurity protocols when handling their horses either at home, in the barn, at outside pastures and stables, on the trail, or when participating in clinics and competitions in the company of other outsider horses. One can never be too careful. At the first signs of any respiratory disease in a horse it should be isolated and strict antisepsis measures followed in its care and handling.

“As the summer season advances so too does the opportunity for the spread of many forms of equine illnesses.

“The Saskatchewan Horse Federation will continue to advise its members of any changes in the current situation surrounding concerns of possible outbreaks of the EHV-1 virus.”

~ Mae Smith – Executive Director

In Alberta:

This message from Moore Equine Veterinary Centre was posted on their website today:

“Equine veterinarians in Alberta who are involved in the EHV-1 situation had a conference call today. To confirm, there is 1 confirmed case of EHV-1 in Alberta. Two horses that were in contact have been tested and are confirmed negative as of today (May 17th,2011), on both blood and nasal PCR testing.

“There are two other horses with mild temperature increases that are still being tested. there are NO deaths in Alberta as of May 17th,2011. The horse that tested positive is being treated well and is recovering from mild neurologic signs.

“It was the consensus of the 7 veterinarians on the conference call that non cutting or reining competitions are at a very low risk at this time.

“We recommend that owners follow common sense bio-security precautions. We will post a bio-security link as soon as possible for your reference.

“This group of Veterinarians will be monitoring this situation daily and are planning another call early Friday, May 20th, 2011 in Alberta.”

~ Greg Andrews, DVM

Additionally, Burwash Equine Services, of Calgary, as of yesterday, reported they have no cases.

In British Columbia:

There are three confirmed cases in Vernon. These horses were at the Ogden show and all three have been contained and are being treated.
This posted by Paton & Martin Veterinary Services Ltd., Aldergrove, B.C.:
“First of all, there is no need to panic but we must be careful. We are monitoring the situation closely and are in contact with veterinarians in the area and the USA.  

“There has been an outbreak of a neurological form of Herpes virus disease referred to as EHV 1. The outbreak is associated with horses that attended the recent Cutting Horse championship in OGDEN, Utah. This is a similar virus but different strain of what we refer to as “Rhino”. We vaccinate against the respiratory and abortion form. These vaccines do not protect against the neurological form. No vaccine in the market claims that is effective against the neurological form of the disease.

“Despite rumors to the contrary, following conversations with veterinary colleagues in the Province, it appears that the affected horses have been identified and are confined and quarantined in a single private stable in the Okanagan Valley. TO OUR KNOWLEDGE THERE ARE NO CASES IDENTIFIED SO FAR (May 16, 2011) IN THE FRASER VALLEY. The only horse in the Fraser Valley that was at Ogden, Utah is 9 days post-exposure and is showing no clinical signs.”

In the United States:

A press release received today from the American Quarter Horse Association stated, in part, the following:
“Yesterday afternoon, we participated on a conference call with the NCHA Executive Committee and Dr. Jerry Black about the outbreak of Equine Herpesvirus Myeloencephalopathy (EHM) caused by EHV-1 (Equine Herpes Virus) that occurred at the NCHA Western National Championships in Ogden, Utah, from April 29 through May 8, 2011.

“Dr. Black gave us a current update as to the number horses, shows and states affected by this outbreak and explained if a horse is going to come down with clinical signs of EHM they will do so in 2 – 10 days. Once showing clinical signs, they will be contagious within 12 – 24 hours. The following APHIS link explains the disease,

“According to Dr. Black, it is believed the index horse (the initial carrier) came from Western Canada. Currently there are nine states and western Canada with confirmed cases. It was reported last Friday in Colorado there were two confirmed cases; both horses had been at the show in Utah. One horse died and another is in CSU’s isolation hospital. There were horses that left the show in Utah and went to a show in Bakersfield, California and one of those horses has died; there are three others in isolation at UC Davis. Washington State University has one horse in isolation as well. For precautionary measures, all three vet schools have restricted non-emergency equine veterinary appointments.

“In a preventative move, the board of directors of the Breeders Invitational canceled the cutting event scheduled for May 14-28 in Tulsa, Oklahoma. NCHA canceled the Mercuria-NCHA World Series of Cutting that was scheduled in conjunction with the Breeders Invitational. At this time, Dr. Black reported there were no horses showing any clinical signs that had been in Tulsa.

“The show managers for the AQHA/NCHA Weekend in Montana and Oregon have voluntarily cancelled the events. The NCHA, with advice from Dr. Black are monitoring the other states before making further cancellations.

“NCHA further recommends that all its approved events for May 20 – 22 be cancelled.

“At this time no states have closed their borders. Per Dr. Black, it appears USDA will be taking control of tracing the outbreak as they have requested the list of participating horses from Utah.”

~ Don Treadway, Jr.

Here\’s a selection of important information useful to the subject, and how it may affect your horses, and particularly, your travelling with horses at this time.

This is not an outbreak limited to cutting horses.

While one outbreak appears to have presented at the Ogden, Utah show, there is some information that at least one of the infected horses had already attended or passed through several Canadian equine venues. It is possible the virus was present in Alberta and possibly Saskatchewan before the Ogden show. Please remember, this is not confirmed. The point is, cross-contamination is certainly possible. Consider not only where your horses have been for the past 20 days, but also, who has been in contact with them, whether at an event, or at home.

The best preventative is common sense bio-security.

The virus is transmitted via direct and indirect contact, and to a lesser degree, through the air. Transmitting, or \”shedding\” the virus through respiratory channels is the most common, and generally lasts for seven to 10 days, but it can persist longer. If your horse has been in a high-risk situation, a 28 day isolation period is recommended by the American Association of Equine Practitioners.

(If your horse was present at the Ogden, Utah show, you should let your veterinarian know. And remember, while the disease is not reportable federally, it is in some provinces, such as Alberta.)

Don\’t underestimate the power of indirect transmission such as nasal secretions left on equipment, tack, feed and other surfaces. The AAEP suggests it is “an important route of transmission of the virus. Indirect transmission occurs when infectious materials (nasal secretions, fluids from abortions etc.) are moved between infected and un-infected horses by people or fomites (inanimate objects).

Poor hygiene (such as lack of handwashing) and sharing of equipment are often responsible. People who have touched or otherwise come in contact with infected horses should change their clothes and thoroughly clean and disinfect their hands before handling other horses.”

Whatever event you\’re planning on attending with your horses over the coming weeks keep in mind it has been suggested the virus can survive for up to 35 days, but only if it is an ideal environment.

Some trainer facilities, particularly those which had horses in Ogden have voluntarily imposed isolations on their own facility – no incoming/outgoing horses, no lessons – as a preventative measure. Considering the contagious nature of the virus, this is a pro-active course we should all appreciate.

What is the primary symptom?

Often preceding other signs is the presence of a fever. If you are concerned be sure to take your horse\’s temperature twice a day. This is easily done with a rectal thermometer. If you need a refresher on how to do this, read here. The temperature of a normal horse is below 38.5°C (or 101.5°F). According to Moore Equine Veterinary Center, “It is best if you can keep a record of the rectal temperature trends in your horse. Most infected horses will only show mild respiratory signs including coughing and nasal discharge. Early signs of the neurological form of herpesvirus usually involve incoordination of the hind limbs, urine dribbling or being unable to urinate.”

Is there a vaccine?

While there are several vaccines against EHV available, none of them state any protection against the neurological form of EHV infection. Check with your veterinarian to determine the validity of booster vaccinations in your animal\’s case.

We touched base with Ashley Whitehead at the University of Calgary Faculty of Veterinary Medicine to ask her some questions about the virus and what we can do to help prevent its prevalence in our midst.

There is some discussion that the cancelling of equine events for the next three weeks is in order. Is there wisdom in that, or is it overkill for the situation?
“The decision should be made with a risk assessment of the current situation. Any time we travel to a competition where there is mixing of horses from many locations there is a risk of transmitting infectious diseases. Many of us forget about this risk as we compete so regularly. At this time we don\’t know the extent of the outbreak. Containing this virus is key to limiting the spread.” 

The virus is carried airborne. How great of a distance do we need to worry about? Within coughing distance, or across the farmyard?

“The airborne aspect of virus is limited once it gets past the \”coughing distance\” but it can travel through ventilation as has been seen in previous outbreaks in veterinary teaching hospitals though this is a far less important method of transmission.”

Scenario: horse owner attended a horse show in a facility where two weeks prior, horses from a farm we now suspect was affected, were present. Should horse owner be concerned?

“Before answering I would ask a few more questions. My first questions would be: Are the \”affected\” horses confirmed EHV-1? Was there direct contact between the horses from the \”affected\” farm and your horses? Was there indirect contact (ie you or any object touched these horses, then touched your horse)? In most cases the answer to these questions will be no, but I would recommend monitoring rectal temperatures twice daily to watch for any signs of fever. Remember at this point only one horse has actually be confirmed positive with EHV-1 in Alberta and that horse has been quarantined appropriately. It is important to note that only a small portion of the horses that are exposed to the equine herpesvirus become neurologic. We are all concerned but at this point identifying any new cases (including horses that only get the respiratory form and horses that become neurologic) early and isolating them is key, so monitoring rectal temperatures is very important in any at risk horses.”

Thanks to Dr. Ashley Whitehead, instructor, Large Animal Internal Medicine, Faculty of Veterinary Medicine, University of Calgary, for assistance with this post. Thanks to Western Horse Review intern, Jesseca Johanson, and writer and blogger, Melissa Sword for their help with research.
Thanks to everyone else for checking in, I hope you find this information helpful.
Finally, please ensure you are not spreading misinformation during this time. It\’s unfair, useless and can be detrimental to trainers and owners who are practicing due diligence.






5 thoughts on “You Oughta\’ Know About EHV-1”

  1. Sandy Stewart

    This is the best article I have read on the issue – I believe common sense rather than fear and over reaction will be what stops a possible major spread!

  2. Debbie Fadenrecht

    Thank you for the great info
    It is a concern for lots of people where I board and have printed off the page to post for those who do not have PC or might not see your great set of facts and stats regarding this matter

  3. Melisa Barber

    Thank you so much for your prompt and informative articles. It is nice to have all the “work” done for you, so too speak and just go to one place for all the needed info. on this awful disease.

  4. Kathy Lovell

    Thanks so much, this has cleared up some questions I’ve been asking and being asked about. Was very informative and easy to understand.

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