Asthma is characterized by many factors such as airway inflammation and labored breathing. We have developed a model to mimic these symptoms in adolescent mice. Here, we show how measures of labored breathing (counts and enhanced pause) are increased in mice at multiple ages throughout development that are exposed to aerosolized methacholine, a muscarinic receptor agonist. These results demonstrate the effectiveness of methacholine to produce the labored breathing aspect of asthma.