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Ringworm in Dogs: Detection, Prevention & Treatment

Tips for handling "ringworm," a colloquial name for a skin condition caused by a fungus.

Written by: Melvin Peña

Last Updated on January 22, 2024 by Dogster Team

jack russell dog suffering from ringworm

Ringworm in Dogs: Detection, Prevention & Treatment

Does your dog have ringworm? First of all, banish the thought of wriggling creatures from your mind! “Ringworm” is a traditional and colloquial name for a skin condition caused by a fungus. Early detection of ringworm in dogs, simple hygiene in the home, and keeping your dogs and their accessories clean are key to limiting the severity and spread of ringworm.

dogster paw divider

What is ringworm?

Ringworm is not a worm! Ringworm is a fungal infection also known as dermatophytosis. The fungus that causes the most common types of ringworm is Microsporum canis. The fungus spreads through spores, which can survive dormant for 12 months. These spores feed on keratin, a protein found in hair and the top layer of skin.

Ringworm thrives where there is heat and moisture. This makes ringworm more likely to arise in warmer months, in winter when your heater is running full blast, and in homes with multiple dogs. Weak or still-developing immune systems are at greater risk, so ringworm is more likely to afflict older dogs and puppies. The more dogs you have and the more they come into contact with each other, the greater the risk of infection.

Symptoms of ringworm

The ringworm fungus spreads through contact and is strictly a topical condition, so a quick glance at your dog’s poop will not tell you if your dog has ringworm. From the time that spores come into direct contact with skin or hair, they take a little less than two weeks to grow and cause ringworm symptoms. Only a fungal culture performed by your veterinarian can reliably confirm a diagnosis, but the most obvious symptoms of ringworm give us its name.

Ringworm in dogs appears most frequently on the tail, head, paws, and forelegs as a small red ring where the skin appears scaly and the hair is broken, patchy, or lost. Though mild cases of ringworm run their course in three to four months, it is better for you, your family, and your dog to begin treating ringworm right away. Likewise, if there are more than a couple such lesions and additional symptoms are present, your vet is your best bet to tell you if the problem is mange or a more serious condition.

close up of cat lesion on ear due to ringworm
Image Credit: Yaya Photos, Shutterstock

Treating ringworm on dogs

There are no home remedies for ringworm, but over-the-counter treatment options are both accessible and affordable. Depending on the number of afflicted areas and the severity of the infection, effective treatment of ringworm can take from three to six weeks. Ringworm is a fungal infection, so the primary treatment for ringworm in dogs is antifungal medication.

For mild cases, treatment of ringworm involves antifungal shampoos, ointments, or dips that contain miconazole. Used correctly, miconazole treatments should begin to lessen your dog’s ringworm symptoms within three weeks. You should continue to use miconazole treatments for at least a couple of weeks after the symptoms have cleared to make certain that the infection is gone and that all spores have been eliminated from your dog’s skin and hair.

A lime sulfur dip is another ringworm treatment for dogs, though this solution, diluted in water, has a strong odor. If your dog has multiple lesions or more complex symptoms, your vet may prescribe an oral antifungal ringworm treatment called griseofulvin. A full course of griseofulvin can have side effects and take up to three months. As always, the earlier and more active you are with ringworm treatment, the better, and the less chance that ringworm will spread in your home.

Is ringworm contagious?

Ringworm is a zoonotic disease, meaning it can be passed from animals to humans and vice versa. Just as older dogs and puppies are more susceptible to ringworm, older people, those with weak immune systems, and young children are at risk if your dog has ringworm symptoms. Children should not touch dogs with ringworm, and everyone in your household should wash their hands regularly to prevent the transmission or spread of the fungus that causes ringworm.

Because ringworm is transmitted through contact, it is vital to thoroughly clean and disinfect anything your dog touches -– food dishes, toys, bedding, and brushes, especially –- and to remove dog hair from your home if ringworm symptoms appear. Dogs with symptoms of ringworm should be isolated in a room that is easy to clean during treatment, and dog accessories should be disinfected with a solution of bleach (the ASPCA recommends one part bleach to ten parts water) or disposed of completely. Tile floors and other surfaces your dog is in regular contact with should be cleaned and disinfected as well. Carpets and couches should be vacuumed to remove all dog hair and any spores, which can remain dormant for a year or longer.

Be vigilant!

Since the spores that cause ringworm can lay dormant, even on dogs that do not present symptoms, it is important to stay vigilant. Keep your home, your dog’s home, toys, and accessories clean to prevent ringworm symptoms from recurring. You know what they say: An ounce of ringworm prevention is worth a pound of miconazole!

Featured Image Credit: Nathalie Marran, Shutterstock

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