This one (above) is going to be the biggest challenge, since Buster was successful at demolishing a similar plant at my mum's house a couple of Christmases ago. He silently chewed off the ends of every leaf in one evening, I have no idea if the plant was safe for him to chomp on, but he showed no signs of illness. I am protecting this plant from the cat by keeping it in the studio, which is basically a cat-free-zone. I am also doing my best not to over-water these guys (below). Fingers crossed!
Buster has rubbed up against a cactus before, he didn't seemed phased by it, but the spikes were not terribly sharp. These two cacti are much tougher, should he try to rub his chin on these, he would be in for a painful surprise!