Practical diagnostic approach to the coughing horse

Coughing is a common presenting sign in equine clinical practice which results from chemical and/or mechanical stimulation of cough receptors located within the conducting airways. The presence of a cough is therefore diagnostically beneficial as it confirms either primary or secondary involvement of the airways. Despite its value in anatomically localising the disease process per se, the number of respiratory diseases and disorders which may present with a cough are numerous; hence, further diagnostic investigation is generally required before a definitive diagnosis can be reached. Furthermore, the absence of a cough does not rule out involvement of the airways (Rettmer et al., 2015); in such cases, reliance is based on other less specific localising clinical signs. This review will cover the basic mechanisms which underpin coughing, summarise the diseases and disorders which may present with a cough and provide an overview of appropriate diagnostic approaches which may be adopted in the investigation of the coughing horse.