My dog had a similar situation. We took him in for tests and they said he had multiple tumors. So he had cancer. But he had it for (estimated) a couple of months. So maybe your dog had cancer. But I'm not for sure. Maybe your dog had a respiratory problem
I am so sorry to hear about your dog. While surfing the net for some information regarding my dog's illness (lymphoma), I came across this information about HGE http://yorkieviews.com/hge.htm The symptoms sound a lot like what your dog went through. It sounds like there is no way to prevent this disease from striking. Hope this helps
Did she emitt a really weird smell like rotting meat? If so it was probably parvo. You need to call a vet and explain the symptoms. Any other person you know with pets may be at risk if this is the case. Parvo can travel by foot traffic. You will have to take precautions before you get another pet. And yes even vaccinated dogs can catch parvo.
I m just guessing. Could it be poison?