Today, Meeko, myself, and my housecarl, Argis the Bulwark, were randomly exploring in the Haafinger hold. It was late at night and rather difficult to see. Eventually, we discovered Clearpine Pond where we encountered a couple of Spriggans. At this point, I was suddenly attacked by what I initially presumed to be a wolf. Then, to my horror, I realized it wasn't a wolf at all.
It was Meeko.
This really surprised me, actually. I was aware that Spriggans could control animals, but I didn't realize that ability extended to canine followers. Once I realized Meeko was under their thrall, I immediately went into blocking mode because I obviously didn't want to hit him back. All the while thinking "Meeko! Nooooo. Whyyyyy?"
I tried to reach the Spriggans to kill them hoping this break their hold over Meeko, but meanwhile, Meeko was hitting me rather hard. Before I could do anything else, Argis stepped in and did what I couldn't, and killed Meeko.
This wasn't the first time Meeko died on me. I had him as a follower for quite a long time, and if he ever died, I'd simply reload a previous save. I was very tempted to do that in this case as well, but after giving it some thought, I decided that from a narrative standpoint, this was too good to turn the clock back on, despite how sad it was.
After Argis and I dispatched the Spriggans, I went on a grief-fueled rage looking for any creatures and/or bandits I could kill in the immediate area. After thirty minutes or so of bloodshed, I rant up to the top of a mountain, took off my helmet, and just stood there for fifteen minutes. I then returned to Meeko's body at Clearpine Pond, and carried it all the way back to Meeko's shack so i could lay his body to rest next to his former master (whose body had disappeared by this time, along with his bed, curiously, and so I just left Meeko's body in the spot where the bed used to be).
Argis and I said a quick prayer and imagined Meeko finally reunited with his former master just as his master hoped might happen one day (according to his journal).