Bleach is an effective treatment for ringworm spores that have shed into the environment, says The Pet Health Library. For treating ringworm infections in the skin, a topical anti-fungal treatment is the preferred approach, according to WebMD.
Wiping down surfaces with bleach diluted 1:10 in water is effective in stopping transmission of the disease, according to the Pet Health Library. However, bleach should not be applied directly to skin because it is very irritating, according to the Jamaica Observer.
Pets infected with ringworm are often treated with oral medications rather than topical ones, states The Pet Health Library. Because the condition is extremely contagious to both animals and people, it is important to also disinfect the animal's fur and the environment in order to prevent spread and re-infection.