Embracing the Cascade part 3: clinical decision making in equine asthma

Abstract

Equine asthma is the current terminology that covers chronic non-infectious lower airway disorders in the horse. Mild and moderate equine asthma reflect the syndrome previously referred to as inflammatory airway disease, while severe asthma reflects both recurrent airway obstruction and summer pasture-associated obstructive airway disease. Corticosteroids are the most important therapeutic agents for the management of horses with all severities of equine asthma. Prednisolone and dexamethasone products are authorised for use in horses and can be used for the management of asthma. Inhaled corticosteroids have the potential advantages of reduced systemic effects and reduced detection times in competition animals. ‘Special’ (extemporaneous) formulations of oral dexamethasone may be valuable in horses with severe asthma. A range of bronchodilator therapies can be used for the management of severe asthma; although the clinical efficacy of systemic bronchodilators still lacks a robust evidence base, they may have a particular role in ‘rescue-therapy’ and in acute exacerbations. The evidence for the use of mucolytic agents is limited and excessive mucus production should resolve with improvements in airway inflammation. Inhaled saline and inhaled acetylcysteine may provide useful improvements in mucus secretion without any effects on competition horses. Mast cell stabilisers may have a role in the management of mild equine asthma, although they have a limited evidence base for their use. The use of the prescribing cascade provides access to a range of medications that are useful in the management of equine asthma.