So I'm heading from Morvunskar to Dawnstar (west of Windhelm) and I see what looks like a Sabre Cat ahead. It looks like it's got some kind of steam coming off it (like from a frost spell), but it was hard to tell due to the night and weather.
Since I'm a lvl 12 Mage with Brelyna in tow, I cast Stoneflesh and Flame Atronach then cut loose with a firebolt.
It runs toward us...
http://imageshack.us/photo/my-images/807/ghostcat.jpg/

I guess I should have followed it, but is was so much a WTF moment that I barely had presence of mind to take a screenshot.

Anyone else run into this? I haven't in several hundred hours. I have mods, but as far as I know none that would do this.
Any guesses?

theres a quest where you have to kill a bunch of ghost animals. cant remember what its called. its from an old dude in a shack in the mountains.

here it is: http://elderscrolls.wikia.com/wiki/Kyne%27s_Sacred_Trials

If it was Froki's quest the thing would be hostile. Maybe it's a summons from a friendly NPC?

Thats true i suppose.

I thought about the Spirit ca from Kyne's Trials, but I haven't been anywhere near Froki's Shack this playthrough.

As far as a summon- is there more than one form for a familiar? Regardless, there were no other creatures nearby. It was way out of range for it to be Brelyna's, and she summons Flamers anyway.
I spotted the cat at the top of a hill. Seemed like a normal spawn.

That doesn't look quite like the Sabre Cat from Froki's quest.... the only time I did that, the cat was bluish transparent, but still had stripes like the normal ones.... Very odd!

I'm on my second playthrough and I never did this quest. That's awesome, I can't wait to do it.

I've seen one too. It was attacking a bear when I saw it.

Thats awesome!
I'll do that quest tomorrow!

(i wish we had more familiars.. I want the Sabre Cat one! They are so cool!)