Ringworm Fungus in Dogs

Ringworm is a disease that actually has nothing to do with worms. In fact, it is a skin disease caused by a fungus. The main symptom is circular lesions, originally thought to be evidence of a worm curled under the skin, hence the name. Ringworm can affect humans and various domestic animals, particularly dogs. The medical name for infections of ringworm is “tinea.”

Ringworm Fungi

Several different fungi can cause ringworm. The species that most commonly affect dogs are Microsporum canis, Microsporum gypseum and Trichophyton mentagrophytes. All will affect a dog with similar symptoms, often via a scratch on the skin, allowing the spores of the fungus to enter.

Location

Ringworm fungus spores are transmitted by contact. They live on the animal or in their living environment. A dog can become infected if brushed with grooming equipment that has come into contact with the spores, or if he lies on a blanket that has been infected. Spores are able to survive outside outside of an animal for up to 18 months.

Symptoms

The primary symptom is a fairly circular lesion on the skin that has become devoid of hair. Sometimes these lesions will have scaly skin in their center. Often these will appear on the head but can also affect the legs and feet. The dog may find them itchy. Occasionally, the lesion will not be circular and spreads across the dog’s nose. A veterinarian technician can detect ringworm by analyzing skin samples or hairs surrounding a lesion, although this can take several days.

Treatment

Most healthy dogs will have some immune resistance to ringworm and never develop the symptoms. However, if lesions do appear, they can clear up on their own, the dog’s immune system fighting the infection, within four months. For more virulent infections, clip the hair around the lesions short and treat the lesion twice a day with antifungal medications such as miconazole or chlorhexidine. A vet may also prescribe oral medications. There are currently no vaccines for ringworm.

Threat To Humans

Ringworm in dogs can be transmitted to humans. This can occur through contact with an infected animal or objects that have been in contact with an infected animals. As with dogs, fungal spores will often enter via a scratch or lesion on the skin, or an area that is excessively moist, such as a patch of athlete’s foot. The symptoms are similar to those in dogs, with a round skin lesion, often slightly raised at the edges. Treatment is with antifungal medication. Those with poor immune systems, such as people with HIV or AIDS, are particularly at risk.