Shadow the lonely cat
(Book)

Kitty has always thought she was allergic to cats, but during a midnight sneezing fit at a sleepover, she learns that the truth is far more magical--Kitty is able to turn into a cat! She eagerly takes her place as the Guardian of the local cats' Cat Council, using her human knowledge to help them solve their feline problems. But Shadow the black tomcat hasn't been seen at a meeting for weeks. In the human world, Kitty hears some of the children at school saying he's a witch's cat. The house he lives in is a bit scary, but that's no reason to let him be lonely. Kitty is determined to help, but she is going to have to use all her new cat skills to figure this problem out! -- from Amazon.