Is Ringworm in Dogs Contagious to Humans?

Many people wonder if ringworm in dogs is contagious to humans or possibly other animals. There are four fungal species that will cause this condition to appear, and all of them are contagious to both humans and some other species of animals.

What Is Ringworm?

Ringworm is not a worm at all, but actually a fungus. The name comes from the appearance on the skin of a circular pattern, which originally led people to think a worm lived under the skin. The fungus survives and spreads by feeding on dead skin tissues and hair. The hair breaks off at the base, leaving small circular patches that are usually found on the legs, paws and face. If the disease progresses without treatment it will spread and form additional irregular shapes on the skin.

How Ringworm Is Transferred

Once contact with the fungus has occurred it will take 10 to 12 days before any signs of contagion appear on the skin. If untreated it will usually run its course in approximately four months. Direct contact with the infected animal or person will spread the fungi. Transfer from infected to non-infected will happen easily from species to species in any combination. Adult humans are less easily infected by ringworm unless they have an open wound that allows the spores to establish. Children, on the other hand, are very susceptible to ringworm and can catch it easily from a dog, cat or another child. The fungal spores are also long-lived and can remain in carpet and bedding for many months, thus infecting pets and people repeatedly. In rare cases, ringworm in dogs has been contracted from contaminated soil, where the fungi can live for several months if the nutrients needed are present.


The vet may use one of three methods to confirm that the lesions are ringworm. Ultraviolet light, or black light, will show approximately 50% of the infecting spores. A sample of hair or skin can also be examined under a microscope to reveal what has caused the lesions, or the sample of tissue can be sent to a lab. This method can take time since a culture must be grown to identify the spore responsible.


Most commonly a topical anti-fungal ointment or shampoo will be prescribed, and possibly an oral medication. The treatment will inhibit any further fungal growth.

Cleaning and Controlling

To prevent further infection of people and pets, careful and through cleaning must be done to remove the fungus. Cleaning of the environment where the pet lives needs to be done in correspondence with the medical treatment, otherwise there will be a risk of reinfection.

A solution of bleach and water on a 1:10 ratio will kill approximately 80% of the spores, and daily vacuuming will help keep them under control. Be sure to use a vacuum that has a bag that can be disposed of immediately after the vacuuming is finished. Be sure to include cleaning any bedding or furniture the dog may use.