GLAD you asked that question!! We have worried ever since the first time we heard Toto do this and it scared us spittless!! I still don't know if there is a way for "laymen" to tell, but our vet kept assuring us it was no problem and although we trust her completely ... we took Toto down to Denver and they checked her inside/out! The vet there said it was indeed reverse sneezing and there was absolutely nothing wrong with her trachea. It wasn't until then that we really stopped worrying about it. However, we still are very careful of her little neck! "Old habits die hard!"