A simple noninvasive method to measure the cough reflex in dogs

Abstract

Introduction: This study describes a method to measure the cough reflex in dogs that is simple to perform, requires no surgical intervention, and can be used to profile efficacy and side effect liabilities of antitussive drugs. Methods: Experiments were performed in propofol-anesthetized dogs in which cardiopulmonary functions were noninvasively monitored before and after the induction of cough produced by spraying 0.75 ml of distilled water into the trachea. Results: The magnitude of the cough response, measured by the frequency and amplitude, was not different for individual dogs performed with repeated trials on different days. Treatment with the opioid antitussive drug, torbutrol (0.055–0.0055 mg/kg sc), inhibited the cough frequency but not the amplitude induced by the water challenge. Furthermore, side effects of torbutrol were identified as mild respiratory depression and an anesthetic-sparing effect with propofol. Discussion: This method offers many distinct advantages to evaluate efficacy of antitussive drugs including the fact that no surgery is required, it takes only 15–20 min to complete an experiment, and it can be used to simultaneously profile antitussive and side effect liabilities of drugs developed for the treatment of cough.