Uhm...I think I know what you're talking about.. my Chihuahua has the same problem..
this could very well be due to a (can't find a more suitable word) "messed up" trachea (sp?)...you know..the breathing tube..thingy? Oh gosh imagine me as a vet huh? LOL
Yeah my dog has this problem..as far as I know, the only thing that would fix it (if your dog has the same problem as mine), would be through surgery or I THINK..not sure but I think there are certain medications you can give your dog but I don't know much about those..
I haven't really done anything with my Chi..he has these little attacks every so often..and he does have some breathing problems..this is more common in small breed dogs...since your dog isn't exactly tiny, I would go see a vet..but...I dunno..my dog is living
*thanks God of course, as always*