This makes sense. My dog spends considerably more time sniffing ground from a pavement renewal project nearby. She may be sniffing smells that were left here decades ago !

Also, a few months ago, an article was shared on HN explaining how dogs are able to detect heat with their nose. And this makes sense too: whenever I shower, my dog starts sniffing and scratching walls near the shower stall, where the pipe is.

I bet she could sense a rat hidden inside a wall or in the ground. Predator™.