A bald spot at the base of the tail is a sure indicator that your cat has fleas – and maybe has even had them for a while. This, along with other signs, can be a symptom of flea allergy dermatitis which occurs when some cats are hypersensitive to flea saliva. To treat the condition and bring your cat’s luscious fur back, get rid of fleas in bedding, carpets, furniture, and apply flea treatment to your cat’s fur directly. A course of antibiotics may be needed if your doctor advises that the infection is serious.