+18 Ringworm Under Black Light Dog Ideas. False positive and false negative results are common, so a black light should not be used on its own to diagnose ringworm. Web ringworm, also called dermatophytes, is a group of fungi that causes infection in the outermost layer of the skin and can also live in hair follicles and sometimes in a dog’s nails.

Web here are some ways to treat your dog’s ringworm: 50% of the microsporum canis species will fluoresce when the woods lamp is placed near the area of hair loss. Web according to wikipedia, wood's lamps have been used since 1925 to detect fungal infections in hair.