Disclaimer: This post was accurate as of patch 3.3.5.
That means for your first two levels with a pet, you have to just keep them alive. Bandage them maybe, if you must.
Find out more here.
This question frequently shows up in my Search Engine hit statistics… apparently a lot of people are curious about this, and reasonably so, you’d think you’d get it at the same time you get your pet, but that is not the case!