Flu can sweep through a barn, leaving horses with runny noses, wheezing and coughing.
While most horses recover fully from flu, they often must be removed from training for weeks while their lung tissue heals. As a consequence, riders lose valuable training time and their horses may be sidelined during that all-important event of the year. This can be particularly frustrating for horse owners who have followed the veterinarian's vaccination recommendations and kept their horses up to date with the influenza vaccine. Veterinarians have long said that many vaccines aren't effective because they don't carry the strain of virus that is circulating in horses and because vaccine makers are not required to show efficacy of a vaccine by conducting challenge studies of vaccines. The vaccine-maker simply must show the vaccine caused an immune response in the horse.