Two Pottawattamie County horses confirmed by their attending veterinarian with equine influenza (EI) also tested positive for equine herpesvirus: one with the respiratory form (EHV-1) and one with EHV-4.
The horse confirmed with EHV-4, an unvaccinated 3-year-old Quarter Horse gelding, presented on March 3 with clinical signs of equine influenza that included coughing, fever, and nasal discharge. He was confirmed positive for both equine influenza and EHV-4 on March 7 and is reported as recovering. Nine additional horses were suspected, and 15 were exposed.
On March 7, an unvaccinated 17-year-old Paint gelding presented with signs of EHV-1, including coughing, fever, and nasal discharge and also tested positive for equine influenza in nasal secretions. An additional 20 horses were suspected and 30 exposed.
All exposed horses are under voluntary quarantine.
About Equine Influenza
Equine influenza is a highly contagious respiratory disease that infects horses, ponies, and other equids, such as donkeys, mules, and zebras. The virus that causes it is spread via saliva and respiratory secretions from infected horses. Horses are commonly exposed via horse-to-horse contact; aerosol transmission from coughing and sneezing; and contact with human’s contaminated hands, shoes, or clothes or contaminated tack, buckets, or other equipment.
Clinical signs of equine influenza infection can include a high fever (up to 106°F); a dry, hacking cough; depression; weakness; anorexia; serous (watery) nasal discharge; and slightly enlarged lymph nodes. Consider monitoring your horse’s health at shows by taking his temperature daily, which can help you pick up on signs of infection early and take appropriate measures to reduce disease spread.
Vaccination is an important and inexpensive way to protect your horse. US Equestrian requires proof that horses have had an equine influenza vaccination within the six months prior to attending organization-sanctioned competitions or events. Your veterinarian can help you determine what other vaccines your horse might benefit from.
In addition to vaccinating, following strict biosecurity protocols can help reduce your horse’s chance of infection and disease. Such measures include quarantining new equine arrivals at barns, disinfecting buckets and equipment, and preventing nose-to-nose contact between horses.
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 myeloencephalitis (EHM, the neurologic form).
In many horses, the first or only sign of EHV infection is fever, which can go undetected. In addition to fever, other common signs of EHV 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.
Horses with EHM 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.
Herpesvirus is easily spread by nose-to-nose or close contact with an infectious horse; sharing contaminated equipment including bits, buckets, and towels; or clothing, hands, or equipment of people who have recently had contact with an infectious horse. Routine biosecurity measures, including hygiene and basic cleaning and disinfection practices, should be in place at all times to help prevent disease spread.