How to Treat Ringworm on a Dog. Ringworm is a contagious fungal infection that is common on dogs. This fungal infection can be passed on to other pets and to humans, particularly children, so it is important to begin treating a dog's ringworm as soon as it has been diagnosed. There are several different treatment methods available and your vet will recommend one based on your particular dog.
Administer an oral medication if recommended by your vet. For some cases of ringworm on a dog, particularly if it has spread to more than one area or is a large lesion, your vet may prescribe an oral medication like Griseofulvin or The Program, a flea prevention product with anti-fungal properties. Oral medications will combat ringworm from the inside out.
Apply an anti-fungal cream to your dog's ringworm lesion(s). This will help the infection heal as well as help decrease environmental contamination.
Shampoo your dog's coat with an anti-fungal, medicated product. Generally, the shampoo lather should be left on your dog for ten minutes or so before you rinse it off.
Use lime sulfur dips several times a week to help control the transfer of ringworm spores into the environment. This can be done at home although the dips do not smell very nice and they can stain fabrics.
Treat the environment to prevent the spreading of the infection to other pets and family members and to prevent re-infection. Use bleach on areas, fabrics and pet bedding that can handle it. Vacuum carpets regularly and dispose of the vacuum bag after each use. You can also consider having carpets steam cleaned, getting rid of all pet items and washing down walls with a bleach solution.
Clip the dog hair around the ringworm lesions only if this is recommended by your vet. While this was often done in the past, it has been shown to increase environmental contamination by spreading active ringworm spores.