I haven't personally come across one of these but have seen them transcribed before. Unfortunately the photographer of this one hasn't linked the photo to a photo of the owner's grave so it's difficult to tell exactly which grave it belongs to.
The photos are time stamped, but even with that, it would be a guess as to which grave to link it to. You could try contacting the photographer to see if they could shed any more light on it or not.
While BG is definitely meant for human only remains, I personally don't have anything against pet graves being included as long as they are clearly identifiable with the owners grave. Pets are a huge part of some peoples lives and are often valued as much as children, or in fact as a replacement for children. A future family historian may find this information invaluable and often not found in any other place.