My Rainbow Bridge Keisha died from what is call Gastrointestinal Illness or Canine Bloat.
Technically known as gastrid dilatation and torsion complex, canine bloat is an intensely painful, lifethreatening condition in which gas, air and fluid build up in the dog's stomach, causing it subsequently to bloat and ultimately twist. This acute trauma hits suddenly and violently. As it progresses, the internal turmoil squeezes the veins and arteries that transport the body's blood supply and impairs the dog's ability to breathe. Soon after the dog will die.
Bloat is a condition that requires immediate, emergency veterinary attention. Your veterinarian, by inserting a stomach tube through your dog's nose, may be able to release the gas buildup in the stomach. If at this point the stomach has twisted, no such release is possible, and surgery to untwist and anchor the stomach is the only option. To further complicat matters, the prognosis is always uncertain.

This is very hard for me to talk about (I still feel guilty, becase I think it was all my fault).
If you would like to go & read the story I wrote here is the link Keisha's Story.
What happens to her starts at the bottom of the first page & continues on the next page.
Sorry I can't just tell you It's still too painful).