Hi Sam,
Quirky cats definitely keep us on our toes. Some cats do VERY poorly in confined spaces- whether its territorial behavior or anxiety about the loss of control, i don't know. I agree with you about not preventing access to his cage- it's his safe space and these feelings almost certainly come from a need to feel safe.
If he's the only occupant of the room and the cage door stays open, can't you put food/water and litter box on the floor of the room? I'd give that a try to reduce invasion of his personal space. And I'd REALLY try to find a foster home for him. In my experience, 99% of these cats do really well once they're in a more secure environment, and i expect it will go away.
The other thing i'd do if he's not going to into foster in the next few days is a longer acting medication, since he clearly is experiencing stress and anxiety. I've had really good success with fluoxetine with this type of cat, but please talk to your veterinarian about it :).
You could also classically condition him and associate approach of his space with something really good. E.g., 2 - 3 times per day, take a step toward his cage and then give him somethign he LOVES (canned food on a spoon, special treats, a tiny bit of tuna), and doesn't get other times. Over time get closer to his cage. The goal being for him to learn that when you approach his cage, good things happen.
Dr. Sheila
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Sheila Segurson, DVM
Diplomate, American College of Veterinary Behaviorists
Maddie's Fund
9258608284
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