They make caps for those blocks if you don't want to fill them but I don't know how sturdy they are to set kennels on. They nicest setup I ever saw was from a bricklayer who made his kennels that way. He had a gutter set up on the end and hosed everything between the walls.
Funny thing, my buddy I helped with his is a brick layer lol, the kennels aren’t sitting on the blocks , we poured a slab and left rebar sticking up where the holes of the bricks would fall out to give the concrete something to bond to while filling up the blocks...
