Straight from the Horses Mouth

Duane A. Lienemann,

 UNL Extension Educator,

Webster County

May 20, 2011 Edition

How many of you remember the cow that stole Christmas? Nobody really had heard about Mad Cow Disease until December 23, 2003. I will not forget that day. Think of the ramifications that had on the agricultural community. In fact it still does. It really didn’t develop like the doomsayers said it would, but that impact is felt daily in what we feed, management practices, marketing, and especially in export restrictions and international trade. This week, it was like déjà vu. Only this time it is the horse industry. It has the same feel, but from a completely different standpoint.
If you don’t know what I am talking about it is. It has hit the equine circles probably even harder than mad cow disease from the standpoint of direct animal loss or potential for loss. If you haven’t heard, there has been an outbreak of a horrid equine disease called Equine Herpes Virus (EHV-1) in horses across several Western states and Canada, and has spread since a horse competition at the Western States National Cutting Horse Association Finals in Ogden, Utah.
Simply put, this is a naturally occurring Herpes virus of horses. Yes, just like cold sores in humans, only a lot worse. Clinically, three different forms arise from this specific herpes virus based on age, stress and pregnancy. They are: 1) “Rhino” which is a self- limiting upper respiratory infection of young horses (< 2 years of age), 2) Abortion in pregnant mares (most in the 3rd trimester but rarely at birth) and 3) equine herpes myeloencephalopathy or EHM, which is a neurologic disease of the spinal cord, and rarely the brain in older horses that can result in death. Unfortunately the horses in question are in the third category. EHM - in this case is being referred to as “Rhino EHV-1”, because this seems to be a mutant strain of the neurological variation of the Equine Herpes Rhino Virus Type 1. The worst part is that there is no vaccine for it, and it can be lethal. In fact there are multiple confirmed deaths due to EHV-1 in several states.
A total of 308 horses from 18 different states and 174 different premises were at the Utah event, and another 689 have been exposed by secondary contact or proximity, according to the USDA. They are in the process now of tracing where each horse that was at the event has been since and what other premises and animals may have come into contact. This will be a formidable task. It does give credence to the push that began after the Mad Cow event for premise and animal ID. So far they have found a total of 45 horses suspected to have become infected with Equine Herpes. Of these 45 horses, 34 have been confirmed to have the disease. Of these 34, 21 horses have the EHV-1, and 13 are confirmed to have the neurologic form, or EHM. To date, 7 of these horses have died or been euthanized. All but one of the 34 confirmed cases involve horses that attended the NCHA competition that was held in Ogden, Utah, from April 29 to May 8.
All horses that were at the Utah event are now quarantined around the country as well as the stables or facilities where they were housed. So far, only horses in Idaho, Utah, Colorado, California, Washington and Canada have been infected with the highly contagious EHV-1, and several other states, including Nebraska, are quarantining certain areas within their states, or halting transportation of horses. Several major horse shows have been postponed or cancelled. Nebraska’s state veterinarian has placed five Nebraska horse farms under quarantine because they had horses that attended the event.
It is believed that a horse with the virus attended the NCHA event in Ogden and may have caused a massive cross contamination. The one most suspected was "Uncle Kunkel" who began displaying neurologic signs while he was stabled on the show grounds. After not responding to treatment, the horse was euthanized. Veterinarians confirmed at necropsy that Wobblers was more likely the cause of Uncle Kunkel's neurologic signs. Extensive postmortem diagnostic testing was negative for EHV-1, thus eliminating him as the source of the outbreak, so the source of the disease is still a mystery. Recent reports indicate that USDA now thinks the source may have been a horse from Canada. Hmmm, think Mad Cow!
There are many variations in the symptoms including: fever, decrease coordination, nasal discharge, urine dribbling, loss of tail tone, hind limb weakness, leaning against a wall or fence to maintain balance, lethargy, and the inability to rise. Infected horses can appear perfectly healthy until they get stressed and the virus takes hold. Horses infected with EHV-1 usually get sick between two and 14 days after they are exposed, and the disease can be fatal if not treated early. The disease poses no threat to people, but it is easily spread among horses and Camelids, which include alpacas and llamas. This happens because it can be airborne and transmitted by touch on about anything you can think of or use in a horse enterprise. It can be by sharing feed, brushes, bits and other equipment. The virus can usually survive for about a week on surfaces, though under the right conditions it could last as long as 30 days making it difficult to contain.

I have already received questions on if this will affect local horse shows, etc. At this point, there have been no secondary outbreaks in the US; however, this outbreak was first diagnosed just a short time ago; incubation is approximately five to ten days; and quarantines are for thirty days past the last sick horse --so things could change. This is classified as an emerging disease because of the degree of the upgrade of severity seen in the symptoms. Because of economic considerations and because of the probability that this outbreak will slowly die out, the state veterinarians around the United States have decided to allow all horses to travel and to attend equine sporting events as long as they have not come in contact with horses that participated in the Utah cutting show or horses from quarantined premises.

The preceding information comes from the research and personal observations of the writer which may or may not reflect the views of UNL or UNL Extension. For more further information on these or other topics contact D. A. Lienemann, UNL Extension Educator for Webster County in Red Cloud, (402) 746-3417 or email to: dlienemann2@unl.edu or go to the website at: www.webster.unl.edu/home