So yea,

I did the quest, got shadowmere, was riding around La-de-da-la-de-daaaaaaaaaaaa (fos ro dah!)
and then SUDDENLY!!!!

A rock trap sprung and MISSED ME!......all together the little rocks and pebbles roll down the hill.
Ha ha ha says me as I walk over them with my shiney new steed.

[censored] YOU SAYS THE ROCKS!
kills my shadowmere.

After waiting 2 in-game months in Towns, My houses, and the spot where the horse died, no shadowmere respawn.

Some light to be shed please?
THANKS!!!

Hmm. I know when you fall the horse absorbs a % of the damage, but I'm not surprised rock momentum did it either. It doesn't take much for Shadowmere to die outside of combat. I'm told Shadowmere has only 3 times the health of a normal horse (and fast health regen), but from my experiences, horses are tanks, and shadowmere is no exception. After tanking a giant, a sabre cat, and a dragon simultaneously with no heals on hard, I'm convinced he's invincible in combat.

Rocks, however, are another story.

I decided to test the death again and bought another horse from a local vendor for 1000g.
I went right back to the same place Shadowmere had died. The trap was reset and sprung again.

None of the rocks were moving and as I just barely brush the side of them while on the horse, I fell off and the horse lies dead.
This is something that needs to be patched. Even though the rocks can be moved while after the trap is sprung, they shouldn't be able to kill a horse
that just happens to walk by.

I have the means to make a video of it if it would better help everyone understand what is happening and why I am curious about the respawning of Shadowmere.

Sounds like those deadly cabbages some other unfortunate poster experienced in a dungeon. They are proven to be hardcoe antagonists in Skyrim.

Are you sure they were rocks, and not cabbages?

Heh!

Absolutely sure...however there is a kettle thrown in the mix with these rocks.

If you start at Helgen and head west staying on the road....keep left at any forks, you'll find the trap.
If you cant find it, that its between Pinewatch and Peak's Shade tower just East of Falkreath.

i was stupid and thought he never died like in oblivion so i left him fight about 20 forsworn and a troll and the next i fast travlled he didnt come
he died ...

http://www.youtube.com/watch?v=WuD0AkeJVhw