I have a 4 year old female heeler. Tonight, she started "coughing" almost like she was trying to cough up a hairball or something, but more like a whisper. I fed and watered her and she was able to get everything down just fine so I don't think there is an obstruction. She coughed off and on for about an hour but now I'm not noticing anything (then again she's in the other room right this moment). Any thoughts on what might cause this? If she's still doing it in the morning I'll take her to the vet.