Is this my grim?

In Harry Potter and the Prisoner of Azkaban, Harry thinks he's seeing a grim, a large dog that appears before death. A strange dog has been appearing to me around our apartment complex. No one else is ever around when I see this dog. Sometimes it's on a leash, sometimes it's just sitting there. But there's no owner with him. I'll walk by on my way to the mail, see him emerged from shadows, then on my way back from the mail, it's gone!

It always startles me because it is so weird looking. At first I thought it was a shaved chow. Then I thought it was an unwrinkled shar pei. It's medium sized and has a deep, scary bark. I haven't gotten close enough to think about petting it. I tried telling Mike about it but I can't properly describe it.

Well, yesterday I got a picture of the thing:


What is it? And why is it haunting me? If I were the kind of person to see a grim, why do I get this one?

I wish I had gotten a close-up photo, but it started barking at me and I was fumbling with a new camera. I got all flustered and took off.