He isn't on heartworm meds but I'm gonna ask the vet on Monday when he goes in to have his teeth cleaned. He very rarely does this, I think this is only the second time he's done it in the last month we've had him. Oh, and he's 6 years old and didn't have kennel cough from the kennel when we first got him and he hasn't been around other dogs cuz he doesn't get along with them.