If the cat's hair follicles are not broken, you can first shave the cat's chin hair, and then wipe and clean it with an alkaline detergent, such as soap, tea, medical alcohol, etc. When cleaning, you need to pay attention to cleaning the black part of the cat's lower lip. Basically, it needs to be repeated several times or with some force to wash it off. Afterwards, the cat's skin may become red, and then you need to apply anti-inflammatory drugs. For example, erythromycin ointment, etc. If it is a more serious case of purulent and broken skin, then it is best to seek medical treatment in time for anti-inflammatory treatment.