Common causes
Fleas, mites, ringworm, bacterial or yeast infection, allergic disease, excessive grooming, pain, and less commonly hormonal or systemic illnesses can lead to hair loss. Some cats lick the hair away without owners ever seeing them groom excessively.
Pattern matters
Symmetrical hair loss on the belly or inner thighs may suggest overgrooming, while circular scaly areas can raise concern for dermatophytosis. Hair loss near the tail base is common with flea allergy. These patterns are clues, not diagnoses.
How veterinarians investigate
Testing may include flea-comb examination, skin scraping, cytology, fungal testing, or a therapeutic trial. If the skin looks normal but grooming is excessive, pain and medical disease should be considered before assuming the problem is purely behavioral.
When should I make an appointment?
Arrange evaluation for rapidly expanding bald areas, open sores, severe itching, odor, crusting, weight loss, appetite change, or lesions that may be contagious to people or other animals. Avoid applying human antifungal or steroid creams without veterinary guidance.