Call off the dogs -- Hugh Hefner looks to be alive and well ... based on what his wife posted Sunday night.

Crystal Hefner -- Hugh's 3rd wife -- uploaded a Snapchat video of herself and hubby having dinner at the Playboy Mansion ... rocking the ever popular dog filter.

From what we can see, Hef looks pretty good for a guy who's 630 in canine years -- despite rumors he went to the big doghouse in the sky.

Side note: Snapchat does let you post old vids, but it also marks them with a frame, so this looks to be genuine up to date footage of Hef.