EHV

On April 18 the Colorado State Veterinarian’s Office received notification that a Weld County horse tested positive for equine herpesvirus-1 (EHV-1).

The Colorado Department of Agriculture is investigating the positive case and has placed the stabled area of the facility where the horse is housed under quarantine. The horse is undergoing treatment and others it might have contacted are being monitored but are not showing clinical signs of the disease at this point. At this time, the affected horse that showed clinical signs of disease is recovering.

“The most common way for EHV-1 to spread is by direct horse-to-horse contact but it can also spread through the air, contaminated equipment, clothing and hands; this certainly highlights the importance of practicing basic biosecurity practices,” said State Veterinarian Keith Roehr, DVM. “Equine event organizers should continue to practice routine biosecurity practices that are effective in the prevention of EHV and other horse diseases, as well.”

Herpesvirus is highly contagious among horses and can cause a variety of ailments in equids, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and equine herpesvirus myeloencephalopathy (the neurologic form). In many horses, the only sign of EHV-1 infection is fever, which can go undetected.

In addition to fever, other common signs of EHV-1 infection in young horses include cough, decreased appetite, depression, and a nasal discharge. Pregnant mares typically show no signs of infection before they abort, and abortions usually occur late in gestation (around eight months) but can be earlier. Abortions can occur anywhere from two weeks to several months following infection with EHV-1.

Horses with the neurologic form usually have a fever at the onset of the disease and might show signs of a respiratory infection. A few days later, neurologic signs such as ataxia (incoordination), weakness or paralysis of the fore- and hind limbs, urine retention and dribbling, loss of tail tone, and recumbency (inability to rise) develop.

Basic biosecurity practices can reduce the risk of exposure to diseases. Key points of a biosecurity plan include:

  • Isolating new animals and those returning from equine events to the home premises;
  • Supplying clean feed and water; and
  • Implementing infection-control practices for visitors and personnel.

Especially important is the isolation of any sick horses. Horse owners are encouraged to contact their veterinarian if illness appears in their herd.

“Effective biosecurity practices lead to fewer health problems for animals and contribute to a longer and better-quality life for the horse,” said Roehr. “When you’re traveling with horses, something as simple as a clean water bucket that you don’t share with other people’s horses can greatly reduce the risk of disease spread.”