I noticed that blood on the wall and am a bit suspicious myself. If someone did that just to get a little air-time, I'd like to put their head in the wall and see how they like it.
I can see how this could happen. Chasing a cat or a rat that went through the hole easily. Once the dogs head went through he could not pull it back the other way because of his ears and his hair. We found a cat with its head stuck in a glass jar the same way. We pulled on the jar and could not get it off, had to break the jar to rescue the cat.