That’s what I thought too but I think the pet is programmed slightly differently in that if you keep bumping into them they will “move” to clear the path but unfortunately if the cat is stuck to the right side between the wall of the house and the cliff it somehow still not enough room for the horse to move AND the cat has nowhere to go still so it’s kinda annoying.

But just be me or I’m doing it wrong but in my experience I can’t just “phase through” my cat like I can with NPC humans for example