No he doesn't...
I'm only level 10 and when I came up against a Behemoth, Dogmeat took roughly 15 hits or more before he died. I took 2
I'd love to see what he's like after I do Broken Steel, but I think the stats he gets after it actually come before it - like Albino Scorpions and Reavers
Strange. I'm on the 360. In my experience, Dogmeat held his own fairly well, in fact, really well before Broken Steel ever came out. That made it all the more heartbreaking
if he died, which made all the players freak out that their dog could die.....
And they Marched on Bethesda.
And Bethesda said, "Whoa! Back up. We'll make Dogmeat be near indestructible so we wont have to read page after page of posts about Dogmeat dying and you be cryin'.
And we'll even toss in a perk for you morons that can barely walk 50 yards without reloading, so that you can always have Puppies!"
But I digress...
now with BS loaded, Dogmeat is dogmeat until I cross the line into Broken Steel territory.... or until about level 20 or 21. I like him. For the plays that I want him around, I want him around for a long time. But I also hate how friggin powerful he is. Go figger.