I have a cat that I found in a snowbank in -19 degree weather. Severe frostbite to ears and paws, but healing nicely. Some brain and optic nerve damage due to prolonged exposure to the cold. He is a 4 year old neutered male. When I had him indoors, he would sometimes use the litterbox and other times not. It was always spotlessly clean, so it was not that he would not use a dirty box. I tried different types of litters and he still would not consistently use it. He was not around my other cats during this time. The vet said that it may be due to brain damage because he checked out healthy otherwise. Anyone have any experience with this type of brain injury?