Cause of Immediate Death in otherwise healthy lab-mix

[MelsDad]

My 5.5 year old lab-mix died suddenly yesterday morning within seconds of having a bowel movement. She was otherwise healthy, not overweight, and had been eating, sleeping, and drinking normally. She regularly went to the vet and was up-to-date on all vaccinations, worm, tick & flea medications. It's almost unavailable that it's happened. I can only think of something like an aneurysm, embolism, or heart defect. She barked one time and fell over, took several breaths, her hind legs pulled up (fetal position), she stopped breathing and her legs relaxed. I'm at a total loss. Does anyone have any thoughts?  

[MelsDad]

Thanks for your kind words. I'd do anything to hear her tail thumping on the floor again or her running down two flights of stairs to meet me when I got home. She was the sweetest dog I've ever known. The joy has evaporated from our home.

[Ghilly]

I am so sorry for your loss. No matter how long they are with us it is never long enough.

Of course, the only way to be certain what it was would be to have the vet perform a necropsy.  From the sounds of it, however, it was either cardiac-related or some type of neurological episode.  Short of doing regular MRI on our pets, there is no way to foresee these things, so please don't blame yourself for anything.

Again, my deepest sympathies to you on your loss.

Ghilly