Ringworm is actually not a worm but a fungal infection. Dogs get this infection from other dogs or cats that have it. It is contagious and can pass on to humans. Children are the most susceptible to it so you need to get your dog diagnosed and treated as soon as possible. You may be able to identify ringworm yourself if you have ever seen it before. It shows up in a circle. On a dog it may look like a circle where the fur within that region is missing. Only a Vet can give your dog the official diagnosis, however.
Take your dog to a Vet for proper diagnosis. The Vet can take a sample of your dogs fur and place it under an ultraviolet light. If ringworm is present it will glow.
Give your dog grisiofulvin tablets which will be prescribed by your Vet. It is taken orally for 4 weeks. You can place the tablet inside a piece of meat and feed it to your dog that way. This medication must be taken daily.
Put on a pair of disposable gloves and clean the infected areas with Betadine. This will kill the fungus. You will want to clean the area twice per day and throw away the gloves each time. You may want to do this in a bathtub so that you can easily clean up when you are done.
Give your dog a bath using anti-fungal shampoo. You could also use a dandruff control shampoo. Lather your dog up and keep him soapy for about ten minutes before rinsing him clean. Do this every three or four days until the ringworm appears to be clearing up.
Vacuum your house each day and then discard the vacuum bag. This will prevent the fungal spores from spreading to other pets or people in your home.
Clean all of the dogs bedding and soft toys by throwing them in the washing machine on hot water with a cup of bleach and your regular detergent. This will kill any fungus that was living on them.