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Ringworm Infection in Dogs

Although the name suggests otherwise, ringworm is not caused by a worm at all-but a fungus. This highly contagious infection can lead to patchy areas of hair loss on a dog, and can spread to other animals-and to humans, too.

What Are the General Symptoms of Ringworm?

Classic symptoms of ringworm include lesions that typically appear on a dog's head, ears, paws and forelimbs. These lesions can cause patchy, crusted circular “bald spots” that sometimes look red in the center. In mild cases of ringworm, there may be just a few broken hairs, while bad cases of ringworm can spread over most of a dog's body. It's also possible for a dog to carry the fungus and not show any symptoms whatsoever.

Which Dogs Are Prone to Ringworm Infection?

Puppies less than a year old are most prone to infection, but malnourished, immunocompromised and stressed dogs are also at a greater risk than healthy animals. And because transmission of the ringworm fungus can occur via contact with infected animals and bedding, dishes and other materials in the environment where infected hair or scales may collect, ringworm can quickly spread in kennels, shelters and other places where there are many dogs in a close environment.

How Is Ringworm Diagnosed?

Because this fungal infection can potentially spread over a dog's body and infect other animals and people, it's important that you see your vet for an accurate diagnosis if your pet is showing any signs of a skin problem. Your vet may use an ultraviolet light called a Wood's lamp to examine your dog's hair, look at suspect hairs under a microscope, or take a culture of the affected area in order to diagnose ringworm.

How Is Ringworm Treated?

Treatment of ringworm depends on the severity of the infection. A veterinarian may prescribe a medicated shampoo or ointment that contains miconazole or a dip such as lime sulfur to kill the fungus. In some cases, oral medications are necessary to cure ringworm. In severe cases, it may be necessary to use a topical and oral treatment, in addition to clipping away the fur. Once treatment begins, lesions should begin to heal in about one to three weeks.

Please note, it is important to treat your dog for as long as recommended by your veterinarian. Even though the skin lesions may have cleared up, this doesn't mean your dog is cured or can't infect another animal or person. Certain diagnostic tests may need to be repeated in order to ensure cure. And unfortunately, there is no guarantee that reinfection won't occur!