Does your cat have bad breath? The odor that you smell is caused by an infection in your cat’s mouth. The most common cause of infection in your cat’s mouth is periodontal disease, which affects the majority of cat’s over 2 years of age. Of the cats affected by periodontal disease, half of them will develop painful resorptive lesions. Unresolved periodontal disease causes chronic pain; the oral infection can spread beyond the oral cavity to involve organs, such as the kidneys, liver, and heart. Cats need their teeth cleaned regularly just as people do. Home dental care and regular periodontal therapy help to maintain oral health to ensure a healthy, pain-free pet.