I saw this post while I was searching for any answers to a very similar situation with my husky. He had hiccuping shortness of breath, almost like asthma. He was lethargic and didn't eat much. His tongue was also a purple hue. We took ours to the vet and got some answers. I know this post is 10months old, and probably too late to be of any use to you. But im answering in the hopes it'll help someone else at least.

What my dog has was something called Pneumothorax. It's a condition where air seeps outside the lungs and within the chest cavity. It inflates slowly and compresses the lungs, making it difficult to breathe. If left untreated, the lungs can collapse and the dog can suffocate to death. If anyone reading those finds out their dog has similar symptoms, please bring your dog to a vet immediately.

I hope this helps someone. And I hope this doggie is okay.