Dog choking/breathing funnily?

every now and then my dog will start sort of choking weirdly, for no reason that I can see (she did not eat recently last time). its not like a normal choke, its like hyperventilating with a kind of high pitched vocal resonance to it if that makes any sense. She seems normal afterwards ie not panicky, and it generally doesn't seem very panicky. she's a working cross breed springer/cocker spaniel. thanks