He posted it with the art update. It's the artist's dog, the artist who's not late and also delivered content with the news.
The artist who does the side Halloween games by himself to make sure content comes out.
The artist who's art is already done and just waiting on the coder to finish compiling everything.
If they wanted to justify a delay, they'd say it was the Coder's dog, but it's the artist.
People have pets, and pets die. I'd think it was maybe bullshit if it was the coder, but the artist has no reason to lie, and is usually on the level. Plus the art is done, what advantage would lying about this even give? I think it's legitimate.