Female cat with previous UTI peeing in her bed
I have two littermate cats that are 13.5 years old. They have enjoyed their individual beds for years. Last year one cat had a UTI and peed first in her bed, and then in her sister's bed.
Okay, I forgave that bad behavior because of illness. Picked up beds and haven't used them. I purchased two new beds and recently put them down. Both snuggled in and seemed quite content.
After a couple of days/nights, bad kitty peed in her bed. Last night, she peed in her sister's bed. She does not appear to be ill. She is talking, social, eating, drinking, etc.
Unfortunately, good kitty is being deprived of her bed because of her sister. Help me understand this behavior and what do I do?