Nerys, I'm sorry that your question wasn't answered in a timely manner. A bald patch on either side of the tail strongly suggests a flea saliva allergy. Your cat would have denuded those areas by biting at them. Is your cat currently being treated with a flea product? A white anus (or any mucous membranes) would suggest profound anemia. Do his gums and tongue look white to you as well? If not, the white might indicate anal gland secretions. Please respond with further questions or concerns if you wish.
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