Oh Minko!First, I want you to take a deep breath. The key here is that he is breathing normally just now. With that and as long as he has nice/pink gums, we are not in an emergency situation.If he has always had a respiratory issue afoot then he may show increased respiration when on his back (since all his organs are pressing down on the lungs that way -- a reason why we don't like doing midline surgeries in obese animals with that weight on the lungs) and this may be normal for him. The key to that situation is that he was happy and comfortable to lay in that way (if he wasn't, he wouldn't).As well, a few quick breaths with an open mouth is ok (some will do this in play or when using their sense of smell to really get a good deep smell of something). Where we worry is when they open mouth breath continuously at an elevated rate. That would suggest he was in trouble and that would be a sign we need to get him to his vet urgently.So, it sounds like Minko has been giving you a wee scare but as long as he is comfortable at this moment in time, then we don't need to panic and this isn't a situation where he needs to be rushed to the ER.Let me know if I can provide any further help,Dr. B.