Use of alternative animals as asthma models.

This review focuses on the availability, advantages and non-advantages of asthma models in non-laboratory animals (cats, dogs, sheep, swine, cattle, horses, and monkey). Physiology and pathophysiology of the respiratory system as well as methodological aspects differ significantly between species and must be taken into account before evaluating the usefulness of a single species to serve as model for either asthma or chronic airway obstruction. Allergic asthma models have been described in cats, dogs, pigs, sheep, and monkeys. Among these species, the feline one is of particular interest because cats spontaneously develop idiopathic asthma. Currently available allergic feline models are well characterized with respect to lung function, bronchial responsiveness, airway inflammation and lung morphology (remodeling). Other species lacking for collateral airways (i.e. porcine and bovine lungs) are most sensitive to functional consequences of airway obstruction and are therefore suitable to study any obstructive lung disease. Animals of body weights comparable to humans (pigs, sheep, calves) offer the possibility to evaluate pulmonary functions using the same principles and techniques that are applicable to either children or adults during spontaneous breathing (generating lung function data in a directly comparable range). Despite the known disadvantages of being expensive and time consuming and despite limited availability of immunological or molecular tools, large animal models offer the great potential to perform long-term functional studies allowing a simultaneous within-subject approach of functional, inflammatory and morphological changes. This may add valuable information to the present knowledge about the complexity of asthma or other chronic airway diseases.