Ringworm is a type of fungus, not a worm, that can cause infected dogs to develop ring-shaped rashes. A dermatophyte that subsists on the keratin found in the skin, hair and nails, ringworm most commonly occurs on the legs, feet, head or tail of dogs, although they may also develop the characteristic rashes on their abdomens. While ringworm often resolves on its own, your veterinarian can provide treatment options for stubborn cases.
Understanding the Fungus
The term ringworm applies to several different fungi – notably Microsporum canis, Microsporum gypseum and Trichophyton mentagrophytes. These fungi live on animals and in the surrounding environment, and are particularly common in humid locations. The fungus reproduces by shedding spores into the environment, although it also spreads via direct contact. Ringworm may infect any dog, but young puppies and those with compromised immune systems are at greatest risk.
Symptoms of the Rash
In rare cases, dogs can carry ringworm without developing any symptoms. However, most commonly, ringworm presents in dogs as a small, round, scaly, red lesion in which the hair has fallen out. The area may also feature small pustules. Although some dogs do not suffer any apparent distress from ringworm infections, others may experience irritation or itchiness, causing them to lick, bite or scratch the affected areas. It is important to have your veterinarian confirm that such infections are ringworm, as it is possible to mistake the disease for demodectic mange.
Treating the Rash
After diagnosing the infection by taking samples of the lesion and culturing the fungus, your veterinarian will likely trim some of the hair near the site to help keep the area clean. Additionally, your vet may prescribe anti-fungal medications that can accelerate the healing process. Some of these medications are applied topically, directly to the lesion, while others are oral medications. In the case of a severe infection, your vet may prescribe a cocktail of anti-fungal drugs to treat the problem aggressively. In all cases, you must administer the full course of all prescribed medicines, even if the rash disappears before the treatment is concluded.
Use care when treating dogs with ringworm, as humans can also contract these fungi. Use latex gloves whenever treating the afflicted area, and wash your hands thoroughly afterwards. People suffering from autoimmune diseases must be especially vigilant when tending to infected animals. In humans, ringworm often infects moist areas of the body, such as near the groin.