Have Dog Health Questions? Ask a Dog Vet Online.
I agree with the other expert. There really are NO diseases that could be transmitted by a rat bite to cause those signs and ensuing death. Rabies or leptospirosis are the only two diseases your dog could get from a rat, and neither of these would cause death so rapidly. Neither would cause bloody diarrhea and vomiting.
The rat bite was coincidental with her death. I strongly recommend having a necropsy performed to diagnose the cause of her death, and get closure.
Please let me know if you have any further questions. If you are satisfied with my answer, please click on the green Accept button. Positive feedback is always appreciated. Thanks.