So, my one year old lhasa apso was pulling on the leash really hard, for a long time, and on training videos it says to pull them back. Larger dogs use choke chains, so I though pulling on a regular lead/collar wouldn't do any harm. The day after he began to, I think, reverse sneeze. He was snorting like a pig with his neck extended, and snorting continuously for 10-15 seconds. He started doing it yesterday morning, once, we went out for a few hours, returned and he had three episode last night. Today, he has already done it twice and it is only 10am. Help! I think all the pulling on the leash has caused this! Omg, have I killed my dog? Or could this be trachea collapse?