Ringworm on a dog’s belly is caused by skin diseases, most commonly caused by fungi. It can be accompanied by itching, bleeding, dryness, hair loss, etc. and needs to be treated on time. Fungal skin diseases are generally caused by the hair not being dried after bathing or the environment being unhygienic. If the area where the ringworm occurs is small, you can apply ointment or spray medicine. If the area where the ringworm occurs is relatively large, you can choose to take a medicated bath.