Keep Equine Herpesvirus (EHV) In Mind

Horses worldwide face a serious threat from equine herpesvirus (EHV), a common cause of equine respiratory disease. In fact, research indicates horses are three times more likely to get rhinopneumonitis caused by EHV than flu caused by equine influenza virus (EIV). To combat this serious threat, a proper vaccination plan is key.

EHV infections often occur in autumn and winter in weaned foals and yearlings. Meanwhile, older horses are more likely to transmit the virus without showing signs of infection. The damage from infection can be devastating.

The most common types are equine herpesvirus type 1 (EHV-1), which can cause abortions, respiratory disease, and neurologic disease, and equine herpesvirus type 4 (EHV-4), which usually causes only respiratory disease, but can occasionally cause abortion. EHV-1 and EHV-4 infect the respiratory tract and can spread via aerosolized secretions from infected coughing horses, as well as direct or indirect contact with nasal secretions.

Clinical signs of the disease include fever, lethargy, anorexia, nasal discharge, and cough. Although EHV-1 can cause abortion outbreaks, EHV-4 has been associated with only isolated occurrences and is not a risk for contagious abortions.

But equine herpesvirus can cause damage that goes beyond horses themselves. EHV-1 and EHV-4 can cause significant economic harm to the U.S. equine industry. An outbreak of EHV-1 at the Hawthorne Race Course in suburban Chicago, which began in October 2012, resulted in four confirmed cases, two horse deaths, and numerous quarantines, prompting officials to cancel a day of racing. Another EHV-1 outbreak, traced to the National Cutting Horse Association Western National Championships in Ogden, Utah, which started in May 2011, led to 90 confirmed cases and 13 deaths across the United States and Canada.

These outbreaks can force the cancelation or rescheduling of horse shows and competitions, causing economic loss not only to event organizers but for communities where the events take place.

An EHV-1 outbreak following the National Cutting Horse Association Western National Championships caused the cancelation of nearly 380 equine events. Even shows that went on as scheduled took a hit because of fears of the outbreak; the Los Angeles area economy lost an estimated $100,000 in revenue from lodging, food, gas, and entertainment because of reduced entries at the Memorial Day Classic, held annually at the Los Angeles Equestrian Center, in 2011.

By vaccinating horses before exposure, you can help protect them against a respiratory EHV outbreak and economic loss. Some commercially available combination vaccines can offer protection against several other diseases in addition to EHV. Your veterinarian can help you provide optimal immunity for your horses by choosing essential vaccines and recommending when they should be administered, and at what frequency.

Although equine respiratory disease due to EHV is a cause for concern for many horse owners, your veterinarian's guidance and an appropriate vaccination program can help prevent it and help ensure the health of your horses.

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