Equine influenza has spread to nearly 20 premises–mostly Thoroughbred training stables–in the eastern, central, and southern parts of the United Kingdom. “The reason (it’s unusual) is because despite the fact that horses have been very well vaccinated and have very high antibody levels, they are still becoming infected,” according to James Wood, BSc, BVetMed, MSc, PhD, MRCVS, DLSHTM, Dipl. ECVPH, head of epidemiology at the Animal Health Trust (AHT) in the U.K.

Influenza, while typically not life-threatening, can make a horse uncomfortable and vulnerable to other diseases. Infected horses usually need several weeks of rest to avoid long-term respiratory problems. Sick horses spread the virus via aerosol droplets or fomites (objects that can mechanically transport infectious agents, such as brushes or buckets). Clinical signs in this outbreak have included an acute cough, mainly during exercise, and nasal discharge. Fever has been seen, but it has not been a consistent sign. All laboratory influenza diagnoses on U.K. samples are made at the AHT, which has been advantageous.

Officials have been relaying recommendations to horse owners regarding the outbreak (see article #4306 online). But, “we’ve been making more stringent requirements with the equine herpesvirus (outbreak) since it is much more dangerous,” said Wood