The Nineteenth Hole

We buy these foam rubber, ping-pong sized soccer balls for our cats. Female cat has been obsessed with them for years. As part of her game, she’ll yowl loudly at the balls (often after we’ve gone to bed or when she thinks we’re not watching) and she’ll walk around the house with them in her mouth, still yowling. It’s the most bizarre noise I’ve ever heard from a cat that wasn’t injured. When we moved 3 months ago, our male cat picked up the same habit, only his high pitched mew does sound like he’s injured. The first few times I caught him doing it, I thought he’d hurt his clumsy self.

I’ve never seen any other cats do this. It’s hilarious, although the noise has freaked out visitors on a few occasions. Is there another cat like this in the world or did ours manage to develop the same rare mental illness?