A little redness in the middle of the cat's anus may be caused by skin diseases, constipation, diarrhea, inflammation, allergies, etc. You can apply ointment to treat fungi and bacteria, or send the cat to a pet hospital for examination and treatment. At the same time, pay attention to the cat's diet and hygiene, do not feed the cat food that is not easy to digest or too greasy, deworm the cat on time, and clean the cat's litter box in time to avoid the breeding of bacteria.