Dr Thomas Chamber, from the Gluck Equine Research Center at the University of Kentucky, says equine influenza is one of the most contagious diseases of horses and therefore requires a timely and accurate diagnosis to help prevent a major outbreak.
Rapid intervention, including quarantine and vaccination, have historically been the most successful ways to prevent its spread.
"Influenza is a moving target, often changing its viral coat to confuse the immune system," he said in Gluck's Equine Disease Quarerly publication.
"The vaccines have to be periodically updated to keep up with the changing viruses. The only way to keep the vaccines in step with the circulating viruses is to obtain samples of those viruses for testing."
The mechanism for updating the vaccines depends on voluntary submission of nasal swabs from veterinarians to their state diagnostic laboratories or directly to the World Organisation for Animal Health (OIE) international reference laboratories for equine influenza in England, Germany, and in Kentucky at the Gluck Center.
Same-day test results are now possible for equine influenza using commercial rapid detection kits, he says.
However, limiting factors are the expense - the tests cost $US25 to $US50 per swab - and, secondly, the quality of the swab sample.
Samples should be taken early in the disease process. He recommends the use of, at a minimum, 6-inch Dacron swabs in pairs or alternatively uterine swabs.