Species Approach to Inflammatory Airway Disease in Animals

Dogs, cats, horses, and humans develop spontaneous bronchoconstriction associated with airway inflammation and characterized by chronic cough and wheeze. Attacks of airway obstruction are induced by exposure of susceptible animals to antigens (typically hay dust, molds, and pollens).

Effective treatment of allergic airway disease is species dependent because of the inflammatory mediators involved in bronchoconstriction. The pathogenesis of feline asthma differs from allergic airway disease in other species in that cats are exceptionally responsive to serotonin (5-hydroxytryptamine). Serotonin, which is released from degranulating mast cells, appears to be the major mediator of allergen-induced bronchoconstriction in cats. Cats also appear to develop chronic bronchitis, which is similar in clinical presentation to feline asthma; the main feature that differentiates these two conditions is the lack of bronchoconstriction in chronic bronchitis.

In dogs, chronic bronchitis is an inflammatory, chronic pulmonary disease that results in cough and can lead to exercise intolerance and respiratory distress; typically, however, it is not characterized by severe bronchoconstriction.

Equine asthma, or “heaves,” is an inflammatory, obstructive airway disease that typically manifests in middle-aged horses. Attacks of airway obstruction are induced by exposure of susceptible horses to antigens (typically hay dust, molds, and pollens). There is also a syndrome of low-grade inflammation of the small airways that is a common cause of poor performance in young to middle-aged, athletic horses.

Inflammatory airway disease is typically not treated in ruminants or swine.

The goals of treatment for inflammatory airway disease are to prevent recurrent exacerbations of airway obstruction and reduce emergency visits and expenses, to provide optimal chronic anti-inflammatory treatment with minimal or no adverse effects, to maintain (near) “normal” pulmonary function, and to meet the owner's expectations of quality of life for the animal.