American Shorthair Cat

　　Cats have a pair of anal sacs located on both sides of the anus. If the gland openings are blocked, secretions accumulate excessively, or injuries from fights occur, bacterial infection and inflammation may develop; cats will lick or rub their anus. Regularly expressing the anal sac secretions helps in prevention and treatment. If the expressed fluid contains blood or pus, or if it cannot be expressed at all, an abscess may have formed due to infection, and prompt veterinary care is advised. (Source：PetsZone)