August 2011
From the State Vet's Office

All Dressed Up and No Place to Show – Equine Herpes Virus

The famous American philosopher, Will Rogers is credited with saying, "…I never met a man I didn’t like." I am not a famous American philosopher, but I do want to go on record for saying, "I never met a herpes virus I do like." You’ve always heard every family has a ‘black sheep.’ Well, Herpesviridae (the virus family name for herpes viruses) is nothing but ‘black sheep.’ Herpes viruses are very species specific and rarely cross species lines, but they don’t need to. There is at least one herpes virus affecting most warm-blooded species—sometimes several different viruses or strains for a species. In humans, chicken pox, fever blisters, shingles and genital herpes are the Herpesviridae family’s gift to our species. In cattle, IBR is a herpes virus most cattle farmers vaccinate against. In poultry, ILT (infectious laryngotracheitis virus) comes from the herpes family and is very costly to the industry. Cats have one causing a severe upper respiratory disease. It is feline viral rhinotracheitis. Usually you see it in kittens with matted eyes and crusty noses, and they sneeze and won’t eat—bad deal.

Another thing I don’t like about herpes viruses is they will kick you when you’re down. By that I mean, when the host (man, dog, cat, chicken or horse) is stressed, the virus goes into overdrive and causes the physical signs and symptoms we simply call "being sick."

Another bad trait herpes viruses possess is, like the old high school buddy or obnoxious relative who comes by for a short visit and never leaves, once herpes viruses infect you, they are not going away. When the host gets over the initial assault from the virus, the virus just migrates back up a nerve and waits for the next time the stress meter pegs out and it rears its ugly head again.

By the way, did I mention the equine herpes virus type 1 (EHV-1), commonly referred to as rhino or rhinopneumonitis, has four different syndromes it causes? These are the respiratory, abortion, genital and neurological syndromes. If you don’t show, breed or compete with your horses, this may not interest you. However, I suggest you pay attention anyway because, if gas prices continue to climb, we may all be riding horses as a cheaper alternative means of transportation.

If you are in the horse industry and show horses, you have likely heard about the outbreak—mostly out West—of the neurological strain of EHV-1. It was traced back to a large national cutting horse event in Utah back in May and had spread to as many as 10 states by early June. There were at least 84 cases with 12 horses having to be euthanized. The state that lies closest to Alabama is Oklahoma, where several shows and events were cancelled. At this time, we are unaware of any horses from Alabama exposed to this outbreak in the West. In fact, at least 20 national equine events throughout the country were cancelled due to the disease outbreak.

In doing research for this column, I ran across a segment that made national news concerning a rodeo that had the rodeo queen contestants compete on stick horses. (There’s a video on the Internet; just Google "rodeo queen stick ponies.") That got my mind wandering like it sometimes does. I used to do a little team roping. I’m just trying to imagine how that would work with stick horses.

If you show horses, take yours to other equine events, commingle your horses in any way or if you may be considering getting a horse instead of a second car, listen up. Even though there is a vaccine against EHV-1, it is not labeled or proven to be effective against the neurological strain of the virus. That does not mean you shouldn’t vaccinate your horses against the diseases recommended by your local veterinarian. In fact, I will jump up and down, pound on the table and tell you that you are just plain ignorant to trade a good vaccination program for luck. Now that I have told you to get on a vaccination program, you can no longer use the ignorance claim if your horse gets tetanus or gets sick or aborts from rhinopneumonitis, or dies or has to be put down from encephalitis. It will just be plain stupid. (Sorry about getting on my soap box about vaccinations, but I got carried away.)

One of the most important preventive measures you can take when commingling horses at events is to use strict biosecurity. That means do not use common feed or water troughs, or share equipment. If a horse is coughing, steer clear of it. And just like your momma told you, "Wash your hands." Just use good common sense to keep from spreading the virus. The virus can survive in the environment for days to weeks—possibly up to 35 days.

If your horse does contract the neurological form of the disease, there could be a broad range of signs ranging from mild incoordination to becoming completely down and unable to rise. Often the horse may have trouble urinating or may become incontinent and dribble urine continuously. It is, at least in my opinion, always important to get a diagnosis on horses with neurological signs.

Treatment is the same as with most neurological diseases. That is to provide supportive therapy like anti-inflammatory drugs and IV fluid therapy to prevent dehydration. Treatment should be tailored by your local veterinarian to the severity of the disease. Those horses with the mild form of the disease usually recover and those that are down for several days tend not to recover.

The dust seems to be settling from this outbreak. Western states are beginning to resume normal equine activities with a little more caution than usual. The herpes family is beginning to retreat for the time being after costing the equine tourist industry in many areas quite a chunk. It is hard to believe something we can’t even see can cause that much trouble.

I think, just in case team roping happens to go the way of the rodeo queen contest I mentioned, I will go over to my parents’ house and find my old stick horse and brush him down.

Dr. Tony Frazier is the State Veterinarian for the state of Alabama.