I am hoping they are not apart of a FEV experiment at least not an active one. I am hoping they are caused by another form of mutation, like a chemical spill mixed with radiation, like mutant cannibals. Maybe they have something to do with the "Jungle Vault" and a broken radioactive Geck like the plot for the cancelled FO Tactics Two.
Maybe they have something to do with Mr.House and why he has not left lucky 38 in years. He's messing with DNA. I just hope it has nothing to do with FEV. I don't want another Vault or Research/military building full of FEV for a good long while.
Interesting concepts. I think it would have been nice for Mr. House to have had a lad dealing with weird creatures. Who says you can't mix robots with reptile dogs?
I was the first person (at least I think I was) that named this creatures wikia page to Reptile Dog simply because that's what it looked like to me.
Then it seems people jumped on the bandwagon and just went along with it.
So it is in no way a confirmed name.

Well now we know they are called 'nightstalkers' and I still call 'em 'reptile dogs', 'chupacabra' and my all new favorite 'rattledogs'.
I kinda liked them.... I'm glad to see new designs for creatures in the game.
They are certainly new...
Reptile Dog reeks of coolness

Yeah I found their cave and thought: gawd I bet it smells like wet dogs and a reptile petting zoo down here. Cool.
Thats cool. I was a little disappointed when i saw the trailer and thought that those might be the gecko's.
Now that would have svcked.