A couple days ago over 600 hundred concerned equestrians in the Wellington Florida area attended a meeting concerning the most recent outbreak of Equine Herpes Virus or EHV. The outbreak has already claimed the lives of several horses. The outbreak threatens to create havoc in the midst of the Florida winter show circuit.

What is EHV?

Most of you have probably heard of the Rhinopneumonitis or “Rhino” vaccine. Rhinopneumonitis is Equine Herpes Virus (EHV). There are many different strains of the virus including EHV-1, EHV-4, and several others that do not affect horses. Both EHV-1 and EHV-4 cause respiratory tract problems in horses. EHV-1 can lead to abortion in pregnant mares and neonatal mortality. EHV-1 can also cause severe paralytic neurological disease. EHV-1 is the strain currently wreaking havoc in Florida.

EHV-1 routinely causes upper respiratory disease, primarily in young horses. Clinical signs generally include a snotty nose, loss of appetite, and a nagging cough. This presentation of the virus has what is known as a high morbidity but low mortality rate. That is, it is highly contagious and many horses may get sick but most young horses recover uneventfully. This presentation of EHV-1 is not normally fatal.

EHV-1 can also cause pregnant mares to abort their foals late in pregnancy or to deliver stillborn or weak foals that die within days of birth. Some of you may be familiar with the Pneumabort-K vaccine that is given to pregnant mares. This vaccine helps protect against abortion and neonatal mortality due to EHV-1 infection.

The neurological form of EHV-1 is a debilitating disease of the spinal cord sometimes resulting, in severe cases, in paralysis. Horses with this form may at first simply look uncoordinated. As the virus progresses horses can be unable to stand and can experience lower leg swelling, an inability to urinate or pass manure and reduced tail tone. Rarely do horses develop the neurological form of EHV-1 after first contracting the respiratory form.

Because EHV is a virus, antibiotics are not indicated in the treatment of horses showing clinical signs. Once a horse becomes sick, the only treatment is in a supportive role — maintaining hydration with intravenous fluids, administering anti-inflammatory drugs like Bute or Banamine, administering immune boosting drugs, and slinging those horses unable to stand. For horses afflicted with the neurological from of EHV, those that remain standing have a better prognosis than those that are unable to stand. Recovery may take weeks to months. It should be said that almost all horses recover from EHV infection.

As with many infectious diseases, EHV is spread through coughing and sneezing. Indeed, aerosol transmission of EHV can occur at up to distances of 35 feet from an infected horse! Transmission can also occur in more subtle ways. Contaminated feed and water can be a vector of transmission. Shared and contaminated equipment can also cause infection. Think blankets and other clothing, tack, brushes, trailers, bits, bridles and halters, just to name a few common items!

EHV does not last long in the environment and is easily killed by disinfectants. However, eradication of the virus from a horse population can be much more difficult. A horse, once infected, can become a “latent” carrier of the virus–for the rest of their life! This means that although the horse may not appear sick or affected, in periods of stress (transport, showing, sickness etc.), they may “shed” virus into the environment subsequently infecting others.

Combating infectious diseases such as EHV

Common sense is our best weapon against EHV and other infectious diseases! Follow the vaccination protocol prescribed by your veterinarian. Too often overlooked, practice basic herd management techniques. New horses, sick horses, and horses returning from shows or facilities should be isolated and their temperatures checked and recorded twice daily for at least 7-14 days. At a a facility with a confirmed outbreak, horses should be isolated and “temped” for 3 weeks. Disinfection is key. Be smart, do not share equipment!

Don’t become complacent in guarding against infectious disease. EHV, Strangles, Flu or other infectious diseases could directly affect you and your horse. This year alone, there have been confirmed outbreaks in Europe, Maryland, Ohio, the Meadowlands New Jersey, Colorado State University Vet School, and Wellington Florida. These are just the biggest and highest profile outbreaks. Hundreds of horses have been halted in their transport and forced into isolation protocols. Thousands of horses have been affected with restrictions and testing. A number of horses have been euthanized. Horses of all types have been affected–racehorses, show horses, imported horses and even hospitalized horses!

The outbreak in Wellington Florida has been linked to a recent shipment of imported horses from Europe. The horses were not visibly showing any signs when they were released from quarantine in NY. The state of Florida imposed a mandatory quarantine order for a large number of horses and a voluntary quarantine order for an even larger number. Biosecurity standards have been posted and required under civic penalty for the Wellington show grounds including:

• Limited admittance of personnel into the barns. Only essential individuals are allowed and those that enter must utilize foot baths on entry and exit.
• Wash hands in between the handling of every horse.
• Minimize the use of shared equipment. Disinfect daily and in between each use of any shared equipment.
• Multi-use medications (e.g. Bute, Banamine, Surpass, etc.) must not be shared between horses.

Most of these measures should be standard protocol for horse owners at all times. If you regularly put your horses in high risk situations, you cannot afford to ignore these basic measures.

Visit the Florida Association of Equine Practitioners web site for complete and up to date information on the Wellington outbreak.

This entry was posted on Tuesday, December 19th, 2006 at 10:30 pm. You can follow any responses to this entry through the RSS 2.0 feed. Responses are currently closed, but you can trackback from your own site.