they are looking for specific ones that are in a database

They could be looking for any images without your knowing - there's no guarantee that those images came from a CSAM database.

Its not like they can create a hash for a guy letting his dog on a horse

They could trivially create a hash for a picture of a guy letting his dog on a horse (which would also include other very similar images).

I didn't necessarily mean to claim that they can scan for a concept lacking a fixed image, if that's what you're saying. That would theoretically be possible with enough hashes, but impractical.