There is something black at the corner of the cat’s mouth

Black stuff at the corner of a cat's mouth may be chronic stomatitis. Cats with poisoning and inflammation may have a reduced appetite, like to eat soft food, and have bad saliva, and dark brown secretions will adhere to the hairs around their lips. Currently, there is no effective treatment for chronic stomatitis in cats. Cats facing chronic stomatitis must be mentally prepared for long-term treatment. For example, professional teeth cleaning, home dental care, and extraction of teeth with poor recovery are the top priorities. Medical treatments include antibiotics, steroids, immunosuppressants, immunomodulators, topical ointments, and hypoallergenic foods.