Anything marked as 'Landmark' is there for Dog to 'mark' as his territory and establish his 'Mabari Dominance' buff in that area. It's also a minor side quest, and you get some exp for Dog marking every landmark item in the game (As well as completion % towards 100%). If you missed Lothering before it's destroyed though, you won't be able to complete it that playthrough.
--- Where's the Kaboom? There was supposed to be an Earth-shattering Kaboom!