“Something’s just not right. He isn’t himself.”

Trying to explain your horse’s poor performance and abnormal behavior can leave you at a loss for words. Poor performance can stem from a variety of issues, and diagnosing it can be difficult for your veterinarian. However, there are a few things we know.

Poor performance often looks like lethargy, reduced stamina during riding and training, and longer recovery from workouts. Inflammatory airway disease (IAD), also known as mild to moderate equine asthma, is the second-leading cause of poor performance, behind lameness caused by orthopedic disease. It’s associated with airway inflammation, coughing, and mucus accumulation in the respiratory tract. It has been shown to occur in up to 80% of 2-year-old Thoroughbred racehorses, although it can affect horses of any age and discipline.

“IAD is considered to be a noninfectious condition, but horses that have had infectious respiratory viruses like strangles, equine herpesvirus-1 (EHV-1), and equine influenza virus (EIV) may be more predisposed to IAD,” says Rob Keene, DVM, equine technical manager with Boehringer Ingelheim Vetmedica, Inc.

In order to minimize infectious causes of IAD, veterinarians often suggest vaccination. Equine influenza virus is a frequent cause of lower-airway inflammation, so it’s important that your horse is vaccinated against the most current strains. Without protection from an updated vaccine, infectious causes of poor performance can lead to high veterinary expenses, as well as days lost in training, riding, showing, and racing. In fact, veterinarians often recommend one week of rest for every day a horse has a fever of 101° F or higher.

“Poor performance can be attributable to a number of conditions,” Keene says. “But we do know that using current and relevant respiratory vaccines may help to minimize the potential infectious causes of IAD, and help keep your horse performing to the best of its ability.”