Which is the most appropriate in 2017: "Mild to Severe Equine Asthma" or heaves, RAO, equine COPD, IAD, tracheal IAD, bronchial IAD, small airway disease, chronic bronchitis, SPACOPD, SPOPD, Summer Heaves or Summer RAO ?

The numerous terminologies employed to describe inflammatory conditions of equine lower airways has led to great confusion in both the equine veterinary scientific and lay community. The terms were modified over time to encompass newly discovered features of equine lower airway diseases. In the age of "Omics", both the volume and rapidity of emerging discoveries now make this approach unsustainable.

Until recently, Heaves or RAO (recurrent airway obstruction) and IAD (inflammatory airway diseases) have been most frequently used to describe these conditions. While they are suitable in research settings as they are differentiated based on lung function measurements, there is considerable overlap between these syndromes, and discriminating clinical signs are not always easily identified. For instance, "respiratory distress" at rest, a distinctive feature of heaves which is absent in IAD, although obvious in appearance, when assessed, is subjective and variable between clinicians (i.e. tachypnea vs distress) and over time.

Non-infectious inflammatory lower airway diseases of horses (IAD, and heaves) share striking similarities with human asthma in terms of etiology, clinical presentation, tissue remodeling alterations and response to therapy. Asthma is a term easily understood by most horse owners, unlike current terminologies, and its easy translation into many different languages facilitates international dialogue on the disease. For these reasons, the medical term "Equine Asthma" has recently been proposed to facilitate communication between all stakeholders. As its clinical features (phenotypes), underlying causes and pathophysiological processes are likely to be multiple, we suggest that Equine Asthma be further defined to encompass currently known phenotypes (mild, moderate, severe, summer pasture, neutrophilic …) and newly emerging endotypes (allergic, Th2, Th17 / mediated…). Based on severity, "Mild or Moderate Equine Asthma" would be used instead of Inflammatory Airway Disease (small airway disease, chronic bronchitis, and the mild forms of SPOPD) and "Severe Equine Asthma" would replace heaves, RAO, equine COPD, SPACOPD, SPOPD, Summer Heaves, Summer RAO (…).