Abstract
A new method for artificially inducing the cough reflex in the unrestrained and unanesthetized dog has been devised. The present method can be utilized for testing the relative effectiveness of antitussive drugs. A monopolar electrode is inserted into the dog tracheal mucosa in such a way as to minimize surgical stress. The most successful electrical stimulation has been obtained from square-wave pulses which were produced by a 1-3 volt, 20 Hz. The duration of the square-wave pulse was 1.0 msec and the stimulation was applied for 5 sec. This stimulation usually produced 3-5 cough reflex. It has been found that electrical stimulation of the tracheal mucosa induces the cough reflex and this phenomenon can be successfully reproduced at intervals of at least 5 minutes duration. Our method allows for a lower threshold voltage for cough induction than those previously published, a greater utilization of each dog and a reduction of time required to standardize the cough reflex and the drug dosage for each animal. As the dogs are caged, there is more freedom of movement, thus the drug effect on posture and general behaviour can be better observed. The method described may be applicable to induction of the cough reflex in a variety of experimental animals.
