My friend has a poodle whom she bought from a petstore.

she had him for about 5-6 years now. But for the past 3 years I've noticed that he had a NASTY cough. At 1st I thought maybe he caught a cold or some type of flu....but when weeks started turning into months & months into years it was clear it is something else. He would stretch out his neck & make a heeving sound almost as if he's having an asthma attack. Sometimes he would bring something up in his mouth & swallow it back down. But most times she has to rub his throat in order for him to stop........so is this kennel cough or something else?
If it is kennel cough how do dogs get it??