I've heard somewhere that using Unholy Frenzy on your pet is what you're supposed to do. Apparently he not only never runs out of energy with the buff, but also melee's like crazy. I had a DK in a raid with me today that had his pet do like 2 million damage, it literally did as much as he did and he pulled almost 43k. I can't link a picture right now (I only have recount and it only logs the last five fights, can I change that?) but I do have the one for our Heroic Hagara attempts.
That is his armory, he's in his tank gear right now though. I'll update next week with his Ultraxion damage. I figure this is really high for using a buff on his pet that he should be using on himself.