Ascaris-induced allergic asthma in the conscious dog: a model for the pharmacologic modulation of immediate type hypersensitivity.

A noninvasive method has been described for producing and assessing Ascaris-induced bronchospasm in the conscious dog and the bronchial responsiveness of a colony of Ascaris-sensitive dogs has been examined over a 2 year period. Both individual and dog-to-dog variation are apparent from the study but the results differ from those of equivalent studies performed by others using anesthetized dogs in that sudden death is not observed. Furthermore, the responses to antigen are not influenced by anesthesia, a procedure that suppresses airway reactivity and pulmonary reflexes. The histamine sensitivity also varied considerably with the different dogs and this corresponded to the sensitivity of the dogs to Ascaris antigen. This model of immediate type hypersensitivity has been used to investigate the effects of bronchodilator and antiallergic drugs.