The terms recurrent airway obstruction (RAO or heaves) and inflammatory airway disease (IAD) are often wrongfully used interchangeably to describe horses with non-infectious respiratory disease. Bonnie Rush, DVM, MS, Dipl. ACVIM, professor of equine medicine at Kansas State University, explained basic differences between the two.

RAO is a common respiratory disease in horses that is characterized by chronic coughing, nasal discharge, and respiratory difficulty. The average age of horses developing RAO is around nine years old. Thoroughbred mares over the age of seven are at the greatest risk for developing RAO. However, all breeds and genders are affected by the disease.

Rush said, "Most of these (RAO) horses I diagnose by physical exam alone, and look for response to treatment. If I treat them (for seven days) and they are unresponsive, I’m going to take chest films."

Because of increased respirations caused by respiratory diseases, using X rays to diagnose RAO is very difficult. But, she said chest X rays will help rule out other types of diseases, such as interstitial pneumonia