Source 2 D0g image that was posted on /v/ in August 2015. The .rar file is the original download posted by the OP, and 
the .jpg is a "completed" version that was posted by one of the users there.

It appears to be a Source 2 of Ashley Wood's D0g model, rather then the one from Half-Life 2.

The model was later found in the SteamVR Performance Test leak and is provided here.