Question about dog veterinarian question?

my old 13 year old chihuahua was fine one day and the next morning his face was really swollen making his eye appear squining, took him to the vet he is on antibiotics and prednisone but it is not getting smaller yet, has only been two days. they think he has an abseessed tooth i am afraid for him to be put under anesthesia at his age to have the tooth pulled. is there any natural or things i can do to help his absess heal and not come back as i do not want hm to go under anesthesia to old for that. please answer if you know of something else for me to try. Thank you. was wondering if a light solution of warm water and asalt poured softly in his back jaw area may help it to heal or not?