Thanks for the input! There has been no change in behavior (other than the ignoring), eating, or sleeping patterns. I guess it could be a far deeper illness than what can be seen (I hope not), so I will take them to our vet after the holiday.
My two thirteen-year-old cats are littermates, and have always been inseparable - sleeping together, grooming each other, cuddling. A few weeks ago, they stopped having contact with each other. There's no spatting going on, just ignoring. I've tried putting them together in their favorite...
