If your cat has bad breath, she probably has an infection in her mouth which is a common reason for odor coming from the mouth. Periodontal disease is the most common infection that causes bad breath and affects most cats that are above two years of age. The majority of the cats that are affected by the periodontal disease will develop resorptive lesions that are painful and destroy the portion of the tooth that is hidden behind the gum line. Some cats suffering from periodontal disease may not show any obvious signs while others may experience bad breath, pain and may drop their food. Periodontal disease is progressive and is diagnosed by closely inspecting the oral cavity. Treatment includes cleaning and treating the diseased teeth under general anesthesia. To treat the resorptive lesions, the affected teeth need to be x-rayed. To treat the recurrence of pain and resorptive lesions, the affected teeth may be extracted. If not treated, periodontal diseases can cause chronic infection and pain. With the progress of the disease, other organs may also get affected such as kidneys, heart, and liver. Oral health for cats is as important as for humans so regular cleaning and dental care should be taken to maintain oral health.