ringworm daschund deadly?cure? dog has ring worm HELP!!!?

ok i have a 2 y/o daschund red short hair unfortunately my mom keeps him out side he has a dog house padded with blanket and towels and he has watcher its rfresh maybe every 3-4 days because he has some left but he has ring worm is it deadly doc gave spec. sham poo a spray and med. non work finished the med and ya please what caused it ?

[metal dish]

help please
its also a plastic dog house