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Herpes hits Maine Farms

Published: 3/26/2010
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By Maddy B. Gray

Emails and panic were flying fast and furious through the equine community recently as news of herpes and quarantine hit the airwaves.

First off, Calm Down!

Secondly, Read Up!

Herpes in horses can be a bit like herpes in people. A lot of herpes infections act like common colds (or cold sores, in our case). No big deal. Very common.
But certain strains have more of a Yikes! element, namely an EHV (herpes) 1 variant. That strain is more aggressive and causes greater concern.

Here's the low-down:

Yes, five horses have been quarantined at their Buckfield, Limington, and Lyman farms. All are doing fine. But they came from out-of-state (New Jersey) farms where horses did have this aggressive (and in some cases, fatal) variant of herpes EHV 1. This variant shows symptoms similar to other dangerous diseases, including Rabies, EEE, and EPM. (See below)
Despite the lack of symptoms, they will be quarantined for 21 days, according to Dr. Beth McEvoy, assistant state veterinarian.
It's a bummer, for sure. It's stigmatizing, expensive, inconvenient, and places an unfair burden on the unsuspecting new horse owners here in Maine.

Yes, there are and were several sick horses at Hemphills Farm in Vassalboro. Again, they were shipped from out-of-state (from Crowley's Auction in Agawam, Massachusetts) and tested positive for Herpes IV, among other ailments. The three horses were then transported to New England Equine Medical and Surgical Center in Dover, NH for treatment.
[These horses are off-the-track thoroughbreds and were purchased from Hemphills by a Florida OTTB rescue organization. Some say they were en route to Canada for slaughter.]
Yes, those horses have very contagious diseases which could be very costly to treat. But their diseases do not require quarantining.

It's frustrating and confusing, right? The quarantined horses are fine. The non-quarantined horses aren't.

To add to the predicament, the herpes vaccine which some horse owners are getting nowadays does not prevent it because it is a new strain.
EHV IV positive horses sure get sick, but they don't die. A simple course of SMZ (sulfamethoxazole) antibiotic can cure them. Again, herpes IV is common, widespread, and it's possible for owners to use good management to prevent it.

Click here for the Agriculture Dept. press release link.

Herpes ain't got nothin' on Hendra

Let's chill and consider ourselves lucky, relatively speaking...Read about Hendra, a heart-wrenching, mystifying, lightening-fast virus which affected an area of Australia recently. It traveled from bat, to horse, to human and left a serious body count. Click here to read more.

If there is any lesson in this cluster of illness and twisted knickers, it points to paperwork. All of these horses came into Maine without proper documentation and health certificates. Maybe that might have raised a red flag, huh?
  • Sick horses should be deemed unfit for sale.
  • Sick horses or well horses from an infected barn should not be released and should not cross state lines.

Read below for more information, provided by the state and other sources:

Equine Rhinopneumonitis is a contagious viral disease of horses and donkeys that is endemic in the vast majority of domesticated equid animals. There are 5 herpes viruses known to infect horses, and the Equine Herpes Virus 1 and 4 are the most medically significant. Neither virus is of public human health significance.

Both EHV 1 and EHV 4 can cause acute fever and respiratory illness, especially in young horses

EHV 1 can be a cause of respiratory disease in weanling foals and 2 and 3 yr old horses
• Most important cause of contagious abortion in mares worldwide
• Commonest cause of viral pneumonitis in neonatal foals
• New equine herpesvirus myeloencephalopathy caused by the hypervirulent mutant (neuropathogenic) strain of EHV 1

EHV 4 most common cause of herpesvirus-related respiratory disease in foals and 2 and 3 yr olds in training

Respiratory disease caused by EHV 1 and 4 are clinically indistinguishable
• After exposure, there is an incubation period of 2-8 days, and horses may develop any or all of these signs: Fever, depression, off feed, nasal discharge, conjunctivitis, cough, pharyngitis, enlargement of lymph nodes of head and neck
• The severity of illness varies with age of the horse and pre-existing immunity
• Clinical signs are not usually seen in older horses
• Both viruses implicated in “poor performance” syndrome in 2 and 3 yr old TB horses in training
• Diagnosis of Equine Herpesvirus respiratory disease cannot be confirmed by clinical signs alone. Clinicians often use a screening test for respiratory viruses and Strep equi (strangles) when determining the cause of illness.

Equine Herpes Virus Myeloencehpalopathy is neurologic disease caused by infection with a mutant strain of EHV1. This disease can occur in horses of any age or breed. It usually occurs following a primary respiratory infection, abortion or episode of fever. Clinical signs are rapidly progressive, becoming worst within 48 hours after onset. There is often mild incoordination, hind end weakness, urinary incontinence due to bladder paralysis, some sensory nerve deficits in the hind end, and in severe cases inability to rise, recumbency and death.

Other diseases can look just like EHV1 neurologic form; the differential diagnosis list includes: Rabies
EPM equine protozoal myelitis
EEE, WEE (Eastern and Western Encephalomyelitis)
West Nile Virus
Trauma, liver failure due to plant toxicosis, bacterial meningitis, motor neuron disease, growth problems such as Wobbler syndrome and more.

NJ Horses Quarantined in Maine

Currently, five Maine horses, located on farms in the towns of Limington, Lyman and Buckfield, have been quarantined and have all been examined by the farms’ practicing veterinarian. None of these animals are currently exhibiting signs of EHV-1 but they are being closely monitored. These horses were imported into Maine within the past week and were potentially exposed to EHV-1 in New Jersey. The New Jersey State Veterinarian announced yesterday that two farms were under quarantine in that state for possible infection with EHV-1. On the New Jersey farms, one horse tested presumptively positive and three horses have been euthanized with clinical signs consistent with the neurological form of the disease.

In an unrelated situation, three horses purchased from a Vassalboro Maine stable were hospitalized at an equine hospital in New Hampshire for evaluation. Two of the horses were clinically normal, and one showed a low fever, nasal discharge and mild increased lung sounds. All three horses were tested using a respiratory virus screening, which included herpes viruses, influenza and Strep. Equi (Strangles)
One filly with no clinical signs tested positive for Influenza type A,
The filly with the fever showed a positive test for Equine herpes virus 4 .
The gelding was clinically normal and tested negative on all screening tests performed.
All three horses tested negative for Strep equi. (Strangles)

As of today, the hospital reports that all three horses are well and clinically normal. The gelding has been released from the hospital. The fillies were retested yesterday to see if there is still any viral shedding, and when that result returns they will be released as well.

Neither Equine Herpes 4 nor Influenza are reportable diseases in New Hampshire or Maine as they are so common. Horse owners are wise to practice good biosecurity including isolation of any new additions and preventative vaccinations to protect their horses from these diseases.

The Maine Department of Agriculture Divison of Animal Health and Industry strongly recommends that tracks, agricultural fairs and equine training facilites in Maine require that all horses entering their facilities be vaccinated for EHV (rhinopneumonitis) and equine influenza, not more than six months or less than 14 days before entry.
Proof of vaccination should be listed on the Certificate of Veterinary Inspection (required for all horses entering the State of Maine) or on a certificate of vaccination signed by the owner’s practicing veterinarian. (Please remember that any horse entering the State also needs to have a negative Coggins test within the previous 12 months). While there is general consensus that vaccination for EHV does not prevent infection with the neuropathogenic strain, it is believed that vaccinating may lessen the severity of an outbreak by reducing viral shedding in vaccinated horses.

View Reader Comments:

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3/26/2010 Margy
This is some really good information. Thank you Maddy!
3/27/2010 Nora
you are amazing Maddy - Thank you. This information is great.
3/27/2010 Jan
Thanks Maddy for helping all of us sort this out. In reality ... the sky really isn't falling ...
3/27/2010 Christine
It's really nice reading your articles and seeing someone besides myself is so on top of the seriousness of these things. So many people either become way too complacent or just don't know any better when visiting places like Hemphils and don't take precautions when going into their own barn after walking the grounds at other farms. Or worse yet visiting there friends to tell them all about what they saw at these other farms, not paying any attention and walking & touching horses all over the place. Hence spreading problems in their own barns w/no regard to diseases they have walked thru in other areas. I have been to see the shipment at Hemphills, lot of problems there, no comment any further details. However they will all end up at camps like that. Oh, my aching heart, I should just stay home and love my horses. I don't need to see anymore. Thanks so much for keeping us in the loop with your work.
3/27/2010 Cindy
Great information Maddy. And thanks for pointing out how our news channels here in Maine like to sensationalize everything! My dear old father used to tell me "don't believe anything you hear, and only half of what you see"....he was a very wise man!
3/28/2010 Arlene
Thanks Christine you said it all for me ...
3/28/2010 Lauren
I still wont touch any horses over in vassalboro... They just bring in diseases...EHV, strangles, and influenza all go through the auction curcuits (not say its their fault, but they should quarantine horses too not just through them into the lot..) and just touching their horses can bring it into your barn! No thanks! Great info though!
3/28/2010 Sonia
Thank you for this great article, Maddy! If we all vaccinate, take sensible precautions and research, we will all be calmer and better-informed. Thank you for putting it all in perspective!
3/30/2010 Elaine
This is why we need a full health check for animals going across borders. We have so many horses in Maine that need to be rescued. We don't need to go rescue out of state.
4/1/2010 Jen
I brought in a horse from Camelot myself and take great umbrage to the statement that we should save Maine horses first. I guess some people think I should have let this very nice, well-mannered, 13 year old horse die because he didn't come from Maine... I suppose you're entitled to your opinion. I think Big Mac would disagree, though. I know I do. I guess to me it doesn't matter where they come from if they are in peril. If I'm in a position to help when help is asked for, geopolitical boundaries do not matter to me. To me, a horse about to die in NJ is just as worthy of rescue as one in Maine. By the way, Camelot does see its share of horses that originated in Maine...
4/1/2010 Jen
K-D Stable in Lee will be hosting an equine seminar on April 10th to benefit First Light Farm Equine Rescue & Shelter. Among other topics to be presented, I will be there briefing on the topic of quarantine protocols so if anyone is interested in learning more about that, please attend! FMI, contact Andrea at First Light Farm.

"While there are many things you can fake in life, pretending that you know horses when you don't isn't one of them" - Cooky McClung