I’ve never actually played, so this might be standard practice anyway, but I think this would be a great time to have the DM roll privately for each player and not tell them if they passed or failed. If the players only know what their character saw (and not if they pass or fail the check, or even get an idea based on the roll) then metagaming is impossible. This could produce a situation where it’s just a dog but the paladin thinks they saw a monster because they failed the roll, or it could be the other way around.
Doing it with DM-only rolls ensures the players have to actually figure out what they saw rather than knowing based on what they rolled or if they passed.
As I said, this could be standard practice, I have no idea. But I hope it is.