A big problem with pets (Wolf and Iron Defender) is survivability, particularly in Epic. Most of that is because Epic mobs are balanced assuming a player with a whole suite of defensive gear (Conceal/Incorp/Dodge, PRR, etc.) plus defensive enhancements and EDs, and the ability to intelligently avoid damage. All pets get is Improved Evasion (which of course is great) and AC (which is not so much). And one armor slot, which means maybe one blue augment. Not a lot of flexibility. Though they do get a buttload of HPs, which makes up for their lack of AI.
What I'd suggest is a schedule of basic autogrant gear-type affixes, simulating the type of gear that Epic monsters are balanced for, to keep pets at an acceptable "baseline" survivability in real-game scenarios
Dodge: 2% per 3 levels (so 20% at eventual cap for a pure char)
Incorp: 1% per 3 levels
Conceal: 2% per 3 levels
PRR: 2 per level
MRR: 1 per level
AC: revisit AC levels after the Armor update, make sure they're at a basic functional level
Permanent Deathward at L8
Repair *and* Heal Amp: 1% per level
Fort: 2.5 per level
All Saves: +1 per 5 levels
These may need to be tweaked up/down for Wolves, I'm writing mostly from an Iron Defender point of view. While 20% Dodge, Ghostly and Blur along with 30% Amp, 60 PRR and decent AC with Improved Evasion and a big pool of HP would sound enviable for most players, keep in mind that pets have no appreciable offensive abilities, no short-term defensive boosts like Uncanny Dodge, cant self-buff with things like Displacement, have no Epic Destinies or Epic Moments, etc. And their alignment is always Stupid Stupid, they'll sit there and soak up hits like a pain sponge. And their aggro generation isnt enough to be truly reliable meatshields.
I think this would just allow for pet classes (non splashes, anyway) to keep a reliably survivable pet at all levels, without necessarily creating an invincible pet (at least no more invincible than a player is in a given difficulty), a pet that could solo a quest for you, or an otherwise overpowered NPC.