What does a ringworm look like on a dog?

Many people are surprised to learn that ringworm in dogs is a skin condition caused by a fungus, not a worm—it’s named for the ring-shaped, scaly sores it often causes. While that may lessen the gross-out factor, it doesn’t make it any less of a problem. The fungal infection can get worse over time and is highly contagious. That’s why it’s important to seek treatment at an early stage when symptoms first appear. 

Ringworm is caused by a type of fungi called dermophytes. According to the Centers for Disease Control and Prevention, about 40 different kinds of dermophytes can cause ringworm. The fungi live and feed on the top layers of skin, hair, and nails. 

Ringworm is more common in cats, but dogs can also catch it. Dogs get ringworm from coming into contact with infected animals, people, dirt, or surfaces like bedding, furniture, or grooming tools. 

Ringworm doesn’t infect every dog who’s exposed to it. “Typically, it’s hard for a ringworm infection to take hold in animals and humans with healthy skin and a robust immune system,” Allison Brys, DVM, co-medical director of VCA Sawmill Animal Hospital in Columbus, Ohio, says. “But some factors can make dogs more vulnerable to ringworm.”

• Age: Puppies and senior dogs have weaker immune systems that aren’t as naturally resistant to fungi.
• Environment: Being in a group animal setting such as a shelter, pet store, or kennel increases a dog’s chance of being exposed to infected animals.
• Medical conditions and medications: Some ongoing medical problems and medications can lower the immune system’s ability to fight off germs.
• Behavior: Dogs that like to dig are more likely to come into contact with fungi spores (microscopic seeds) in the dirt.
• Breed: Boston terriers, Yorkshire terriers, and Jack Russell terriers are more susceptible to ringworm infection. 

Ringworm symptoms can take up to three weeks to develop after exposure. The most common places to spot ringworm infection are on a dog’s face, ears, feet, and tail. 

In the early stage of ringworm in dogs, there may be only one or two unusual spots. You may notice round hairless patches with pink, scaly sores. The sores aren’t always circular and sometimes they look more like pimply bumps or may have a scab. 

Typically, ringworm isn’t itchy, but some dogs may scratch. Claws that break easily or become brittle and rough can be a sign of ringworm too. Without treatment, the infection may spread creating large areas of hair loss and scaly skin. 

illustration of dog with ringworm symptoms

Eventually, ringworm usually goes away on its own. But during the months it takes to heal, it is possible to pass it on to other pets and people. Treatment speeds up recovery and minimizes the spread of infection, Brys says. Head to a vet if you see bald patches or sores on your dog. 

To check for ringworm, vets frequently use a Wood’s lamp (also known as a black light). Some types of ringworm glow green under its ultraviolet light, though it can still be possible your dog has ringworm if there’s no glow. Your vet can also look at a hair sample or skin scraping from your dog under a microscope to confirm the presence of the fungus, or they may send it off to a lab for analysis.

If your dog has one or two ringworm sores, a home remedy could work, Brys says. Ask your vet if a topical ointment for athlete’s foot might be an option. It should contain antifungal medication like clotrimazole (or another medication ending with ‘zole’). 

Oftentimes, vets treat ringworm with a combination of antifungal therapies. Your dog may need medicated ointments or shampoos as well as an oral medication like terbinafine, fluconazole, or griseofulvin. 

The surest way to beat ringworm is to follow your vet’s treatment plan, even if your dog’s skin and fur look better. Treatment can last several weeks or months. If you stop too soon, ringworm will return. Your vet will test your dog at follow-up visits to see if ringworm is still present.

Remember, your pup will continue to be contagious for at least three weeks after starting aggressive treatment. It’s important to separate your dog from areas where other pets and people are during the treatment period. Also, wear gloves and wash your hands every time you interact with your dog to avoid spreading it.

Yes. Ringworm is a zoonotic disease, which means it can be passed among different animal species, like a cat to a dog, and to humans. The fungi that usually cause ringworm in dogs (microsporum canis, microsporum gypsum, and trichophyton mentagrophytes) are easily spread to others. You and your pets can get ringworm by direct contact with an infected pet, person, or contaminated surface.

To prevent ringworm from spreading to other pets or reinfecting your dog, it’s crucial that you disinfect your home. Ringworm spores are easily spread through shed hair and skin cells. They can live on surfaces for years unless you disinfect them. Areas that may be contaminated include:

• Bedding
• Clothing
• Carpet
• Grooming tools
• Furniture
• Food and water bowls
• Pet carrier and toys

Wash fabrics and sanitize surfaces with a diluted bleach solution wherever possible, Brys says. If you can’t wash something (like your couch), go over it with a vacuum. Getting rid of ringworm spores is key to stopping its spread.

Also, dogs who spend a lot of time outdoors may need a medicated bath once or twice a week to prevent ringworm infection, Brys says. Ask your veterinarian what antifungal shampoos they recommend.

Ringworm takes effort to treat, but it is possible to battle the fungus successfully. And while you’ll need to be vigilant about treating your pet’s infection and disinfecting your home, your consistent hard work will be worth it in the end. Just remember: the fastest way to help your pet’s skin clear up and stop ringworm from spreading is by following your vet’s treatment plan, so be sure to give them a call if you suspect an infection or have questions about treatment.

While ringworm can appear in a variety of ways in dogs, it most commonly reveals itself as patches of hair loss with a crusty coating. Rarely, dogs with ringworm are asymptomatic, meaning they won't show any outward symptoms (you may want to use your favorite search engine to look for example images of dogs with ringworm).

On some dogs, ringworm patches appear as a grey, scaly patch, while on others they look similar to a scarlet lesion. Young, elderly dogs or those with long hair are more likely to be susceptible to ringworm. 

If you notice any of these symptoms, we recommend bringing your dog to see your vet as soon as possible to determine whether your dog has ringworm:

• Itchiness
• Inflamed, red skin rash
• Reddened skin
• Darkened skin
• Inflamed folds of the skin surrounding nails or claws 
• Circular or patchy spots of hair loss 
• Scabs or lesions on the skin 
• Scales that look like dandruff

How will my vet diagnose ringworm?

If you suspect your dog may have ringworm, bring them into our animal hospital immediately since they will need treatment to be cured. Your vet may use a few different procedures to diagnose ringworm. The veterinarian may examine your dog's skin and fur under an ultraviolet lamp. While this is the most trustworthy test, it takes 10 days to provide findings. 

What are treatment options for ringworm?

Ringworm may be readily treated with oral drugs as well as several lotions, sprays, and shampoos. If your dog or other pets have a history of skin issues, take them to the veterinarian as soon as you discover any symptoms.

Depending on the severity of the infection, your veterinarian may advise treating all of your dogs at the same time. Ringworm can cause hair loss, rashes, and other symptoms that, to the untrained eye, appear to be another illness. If you suspect your dog has ringworm, there are several effective treatments available.

Depending on the severity of your dog's ringworm condition, your veterinarian will assist you in selecting the appropriate remedy for them. The following are the most common treatments for ringworm:

• Topical medication
• Anti-fungal oral medication
• Environmental decontamination (such as deep cleaning a carpet to keep the infection from spreading)

How can I keep ringworm from spreading?

Ringworm is spread by direct contact with an infected animal or through a contaminated substance. If surfaces are not cleaned, ringworm can linger on them or become trapped in the fibers of carpets, curtains, and linens.

A pet may be a ringworm carrier even if there are no obvious signs. Ringworm spores are tenacious and may survive in the environment for a long time, so confine your affected dog to a single room while you treat them. If you heal your dog but do not eliminate the virus from your home, your dog may become sick again.

To eliminate the spores, soft furniture and carpets should be vacuumed thoroughly and regularly, or steam cleaned. Disinfectants should be used to clean any other things. Consult your veterinarian about which disinfectants are effective.

How long will I have to quarantine my dog with ringworm?

Ringworm can endure anywhere from 6 weeks to 18 months, although it is not as deadly as other illnesses or diseases. It will not kill your dog and will not cause irreparable damage. The best thing you can do is confine your dog to a separate room in your house and limit contact with your other pets or family members while the therapy is ongoing.

Ideally, you should try and keep your dog quarantined for about six weeks while you battle ringworm. Although this might sound difficult, it should be infinitely easier, and much less expensive, than having to constantly battle ringworm.

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

Do you believe your dog may have contracted ringworm? Contact Western Carolina Animal Hospital to book an examination with a vet who can provide treatment options.