What The Muck Is That? EHV-1

Each week we investigate one equestrian conundrum in “What the muck is that?” This week we take a look at Equine Herpes Virus.

A Wisconsin boarding and training facility has been quarantined after an outbreak of the highly contagious equine herpes virus (EHV-1). The Wisconsin State Journal reports one horse was euthanized and two more have tested positive and are ill.” – Star Tribune, Sept. 7

What the muck is EHV-1?

There are five herpes viruses that infect horses. EHV-1 and EHV-4 used to be considered subtypes of the same virus, but are now recognized as closely related but different viruses. EHV-1 is commonly found in horse populations worldwide and was previously referred to as the equine abortion virus. Although EHV-1 is well known for causing reproductive disease, it is also known to cause respiratory and neurological disease. EHV-4 is also known as equine rhinopneumonitis virus and is most common among foals and yearlings. Although EHV-4 most commonly causes respiratory disease, it can also cause abortion and neurological disease. Source: UConn

Source: Cornell

Symptoms include:

  • Fever of 102 -107º F that lasts for 1 – 7 days
  • Coughing
  • Depression
  • Going off feed
  • Nasal discharge

Source: Practical Horseman

  • Abortion usually occurs 2-12 weeks after infection.

Source: Equine Disease Quarterly

Signs of the neurologic disease:

  • Up to 14 day incubation period for neurologic signs to develop
  • Mild incoordination
  • Hindlimb paralysis
  • Lying down and being unable to get up
  • Loss of bladder and tail function
  • Loss of sensation to the skin around the tail and hindlimb areas

Source: Examiner

How is it contracted?

  • Nose to nose contact
  • Indirect contact through buckets, clothing, blankets that are contaminated with nasal discharge
  • The virus can travel via aerosol (in the air) for short distances.
  • Following infection, horses may become latent carriers of EHV; virus may be reactivated after stress or high doses of corticosteroids.

How is it treated?

Treatment involves supportive care and treatment of the symptoms. Non-steroidal anti-inflammatory drugs are commonly used to reduce fever, pain and inflammation. In mild cases, complete recovery will occur in a few weeks.

Horses with neurological disease have variable recovery rates. The prognosis is poor if the horse is unable to stand.

Source: Tuesday Horse

How can you protect your horse?

There are two types of vaccines available for use in the horse for prevention of the disease, but their use remains controversial. “It’s controversial,” Lunn explained.”We know that at the moment, we have no evidence that EHV-1 vaccines can stop the development of the neurologic disease. No vaccine has a claim right now for protection against neurological disease. We also know that some of the more potent EHV-1 vaccines can have a very significant effect on reducing the shedding of the virus from the nose in a well-vaccinated and recently boostered horse.”  Source: The Horse

Used with permission from Gabe Clogston.

In the case of an outbreak, infected horses should be isolated.  The stable should be quarantined for at least three weeks. All stable equipment should be disinfected. People handling the infected horses should be sure to wash their hands after handling each horse, dip their shoes in a disinfecting foot bath, and change clothes before working with healthy horses. Some sources suggest that bedding be removed and burned. Barn stalls, aisles and other surfaces should be cleaned and disinfected as well. Although this virus can last for several weeks in the environment, it is readily killed by most common disinfectants.

Do you have experience with EHV-1? Shout out in the comments section.

Go Riding!

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