How to tell if your dog has ringworm (and what to do if they have)

Despite its name, the common canine illness known as “ringworm” isn't caused by a worm at all; it's a fungal infection that affects your pup's skin, hair, and nails.

Read on to learn what ringworm in dogs looks like, how it spreads, and what you can do to prevent and treat it.

Ringworm in dogs - at a glance

• What it is: A fungal skin infection (dermatophytosis), not a worm. Caused by fungi, including Microsporum canis.

• Symptoms: Circular or irregular patches of hair loss, scaly or crusty skin, brittle nails, and possible itching.

• Contagious: Yes, both to other pets and humans. More serious in children and immunocompromised individuals.

• How long it lasts: Treatment typically takes six weeks or more. Dogs remain contagious for around three weeks after treatment begins.

• Treatment: Antifungal shampoos and/or oral medication prescribed by a vet. Don't stop treatment early.

• When to see a vet: As soon as you notice hair loss or skin changes. Don't wait to see if it clears on its own.

• Key risk: Ringworm spores can survive on surfaces (bedding, brushes, floors) for up to two years.

What's ringworm in dogs?

Unlike heartworm (which is very much an actual worm), ringworm is an infection caused by “dermatophytes,” a type of fungus.

It’s called ringworm because it often presents as a circular patch on people’s skin, but this is not always the case in dogs. The fungus thrives on keratin, a protein found in skin, hair, and nails, which is why the infection tends to affect these areas.

There are several types of dermatophytes that can cause ringworm in dogs. The most common are “Microsporum canis,” “Microsporum gypseum,” and “Trichophyton mentagrophytes.”

Each type of fungus has a slightly different way of spreading and affecting your dog, but the overall symptoms and treatments are similar across the board.

How do dogs get ringworm?

Ringworm is highly contagious, and dogs can contract it in a few ways. Direct contact with an infected animal is one possible method of transmission. This can include interactions with other dogs, interactions with cats, or even interactions with wildlife carrying the fungus.

And this contact doesn't necessarily have to be aggressive, like biting or scratching. It can be as simple as touching or rubbing the infected area.

Ringworm fungi live in the skin and hair, so any contact with these infected areas can spread the infection.

Dogs can also pick up ringworm from environments or objects contaminated with the fungus. This includes places like dog parks, kennels, and grooming salons, as well as personal items such as bedding, brushes, and toys.

And unfortunately, the fungus can survive for a long time on these surfaces, just waiting for a host to brush by.

Soil is another possible (though less common) source of infection. Certain types of ringworm fungi live in the soil, and dogs that dig or play in contaminated soil may contract the infection.

Understanding these transmission pathways can help you take appropriate preventative steps to keep your tailmate ringworm-free.

Symptoms of ringworm in dogs

Ringworm in dogs sometimes presents as circular, bald patches that may appear red and scaly. These patches often start small but can spread over time. They may have a ring-like appearance, hence the name.

How to tell if your dog has ringworm

The appearance of ringworm can vary, and it might not always present as a distinct ring-shaped patch.

In some instances, the infection can cause irregularly shaped patches rather than round ones. And the central area may start to heal, making the ring less apparent. Plus, thick fur can hide ringworm lesions, making them less noticeable.

So it’s important to look out for other symptoms as well, including:

• Scaly, crusted skin: The affected area may be flaky and crusted, with inflammation.

• Thin hair: Hair may be broken or sparser than normal, even if the affected area isn’t completely bald.

• Itching and discomfort: Some dogs may itch and scratch at the affected areas, though not always.

• Nail and claw infections: Ringworm fungi love keratin, so the illness can cause your dog’s nails to become brittle or misshapen.

• More unusual symptoms: Ringworm can sometimes cause infections under or deep within the skin, leading to nodules, ulcers, and drainage.

It's important to note that ringworm symptoms can vary widely. Some dogs may show only mild signs, while others can develop obviously severe infections.

Just keep in mind that the former can turn into the latter faster than you’d think, so early detection is extremely important.

If you notice any of these symptoms in your dog, it’s wise to consult with a veterinarian as soon as possible. Early diagnosis and treatment can help prevent the spread of the infection.

How is ringworm diagnosed?

When it comes to diagnosing ringworm in dogs, vets typically start with a physical examination, looking closely at the symptoms presented. Sometimes, they'll order further tests.

Here are some common diagnostic techniques:

• Fungal culture: The most definitive test. Samples of hair or skin cells are taken and cultured to identify the specific fungus causing the infection.

• Wood's lamp examination: A special UV light is used to identify certain types of ringworm fungi that fluoresce under the light. But not all ringworm species glow, and false-positive results are possible, too, so additional testing is often needed.

• Microscopic examination: A microscope is sometimes used to examine hairs or skin scrapings for signs of the fungus.

How is ringworm treated?

Once diagnosed, the treatment for ringworm in dogs generally involves a combination of topical therapies and oral medications.

Topical treatments for ringworm include medicated shampoos, dips, ointments, or creams. In most cases, the dog’s entire body should be treated, not just the obviously affected areas. Topical medications help to reduce the spread of the fungus and soothe the skin.

Oral antifungal medications are prescribed to treat the infection and are essential for eliminating the fungus from the body.

Your veterinarian will also recommend methods for decontaminating your dog’s environment, like vacuuming, laundering, and disinfecting. If your dog's scared of the vacuum, we have a guide for managing that!

The treatment duration can vary, and it'll often last several weeks to make sure the infection is completely gone. Pet parents should closely follow their vet’s instructions; premature discontinuation of treatment can lead to a recurrence.

Dogs remain contagious for about three weeks after starting treatment, so limit contact with other pets and people during this period.

Can humans catch ringworm from dogs?

Yes. Ringworm can spread from dogs to humans. It is a zoonotic infection, which is a fancy way of saying it passes between animals and people through:

• Direct contact with an infected dog's skin or fur.

• Touching contaminated surfaces such as bedding, grooming equipment.

• Not washing soft furnishings where fungal spores have been shed.

In most healthy adults, human ringworm infection is relatively mild, typically appearing as one or more red, circular, itchy patches of skin.

It's usually straightforward to treat with over-the-counter antifungal creams available from a pharmacy.

But the infection can be more serious in certain groups. Young children, elderly individuals, and anyone with a weakened immune system, like those undergoing chemotherapy, living with HIV, or taking immunosuppressant medication, are at greater risk of a more severe or widespread infection.

If you notice a red, ring-shaped or circular patch of irritated skin after contact with a dog diagnosed with ringworm, see your GP or speak to a pharmacist as soon as possible.

Don't wait for symptoms to spread. Human ringworm is treatable, but early action reduces the risk of passing the infection to others in your household.

Keeping yourself safe from ringworm

While your dog is being treated, take sensible precautions at home:

• Wear disposable gloves when handling or medicating your dog.

• Wash your hands thoroughly afterwards.

• Avoid letting your dog sleep on beds or sofas until the infection has cleared.

How to prevent ringworm

Want to prevent your pup from contracting ringworm in the first place?

It’s mostly about keeping your dog's skin and immune system as healthy as possible, plus supervising your dog’s interactions with other animals (and humans).

Fortunately, healthy adult dogs are actually quite resistant to ringworm infections but become more susceptible if they’re suffering from skin damage or health problems that weaken the immune system.

Ringworm prevention is one of many reasons to regularly groom your dog and clean their living spaces.

Bathing your pup with a pet-safe shampoo and keeping their coat well-groomed reduces the risk of fungal infections and lets you pick up on any skin problems as early as possible. And regularly sanitising bedding, toys, and floors can help eliminate any lingering fungal spores.

What should I do if I have multiple pets?

If you have multiple pets and one of them contracts ringworm, keep them in a separate room or area away from other pets and family members.

Make sure this area is easy to clean and disinfect it regularly. Limit direct contact with your pet until they’ve been treated and cleared by a vet. Isolating your infected pet can help prevent its spread to other animals or even to humans.

That last part is worth reiterating: humans can indeed contract ringworm, and dogs can spread it to us. Practice good hygiene by washing your hands thoroughly and changing your clothes after handling your infected dog or cleaning their living areas.

And, of course, you should strictly adhere to the treatment regimen prescribed by your vet, including both topical and oral medications. Regular vet check-ups are important for monitoring the progress of the treatment and making any necessary adjustments.

How to clean your home if your dog has ringworm

Cleaning is one of the most important parts of managing ringworm in dogs. Even if your dog is receiving treatment, fungal spores shed from their skin and coat will continue to contaminate your home.

Left unaddressed, these spores can reinfect your dog, spread to other pets, or be picked up by people in the household. Ringworm spores are remarkably hardy and can survive on surfaces such as carpets, furniture, and grooming equipment for up to two years.

The goal of environmental cleaning is not to sterilise your home, but to reduce the spore load consistently throughout the treatment period, which typically lasts six weeks or more.

Bedding and soft furnishings

• Wash all bedding, blankets, and any soft furnishings your dog has been in contact with on the hottest wash the fabric will tolerate, ideally 60°C or above.

• Where possible, add a pet-safe disinfectant to the wash.

• Run items through the machine twice if you want to be thorough.

• During treatment, consider replacing fabric dog beds with a wipeable alternative that is easier to decontaminate between washes.

Hard surfaces and floors

• Clean hard floors, skirting boards, and surfaces with a dilute bleach solution — one part bleach to ten parts water is effective against ringworm spores.

• Always clean visibly dirty surfaces with soap and water first, then apply the disinfectant solution.

• Bleach will not penetrate grease or dirt effectively, so the order matters. Accelerated hydrogen peroxide products are a bleach-free alternative that is also effective if you prefer to avoid bleach around children or other pets.

Carpets and soft furnishings

• Vacuum carpets, rugs, and upholstered furniture daily throughout the treatment period. This removes shed hairs and skin cells carrying fungal spores before they can settle and persist.

• Dispose of vacuum bags or empty the canister directly into an outdoor bin after every use, leaving spore-laden debris in the vacuum is a common source of reinfection.

• Steam cleaning carpets and soft furnishings mid-way through treatment can provide an additional layer of decontamination.

Grooming equipment

• Brushes, combs, leads, and collars should be soaked in a dilute bleach solution or replaced entirely.

• Don't use contaminated grooming tools on other pets.

• Keep your dog's grooming kit separate from that of any other animals in the household until two consecutive negative fungal cultures confirm the infection has cleared.

Limiting contamination day to day

• Where possible, restrict your dog to one or two rooms that are easy to clean — hard floors are preferable to carpet during this period.

• Keep your dog off beds, sofas, and carpeted areas, and use a washable cover on any surface they rest on. Change and wash this cover frequently.

Consistency matters more than intensity

• A thorough clean once a week is less effective than lighter, more frequent cleaning throughout the treatment period.

• Stick with it. Environmental decontamination and veterinary treatment work together, and neglecting either significantly increases the risk of the infection recurring.

When to see a vet for your dog's ringworm

If you notice any of the common symptoms of ringworm, like circular patches of hair loss, scaly skin, hair loss, or changes in your dog’s nails, it's always wise to schedule a vet visit.

Prompt veterinary attention not only helps in early diagnosis but also prevents the spread of the infection to other pets and people.

If your dog is already being treated for ringworm but their symptoms persist or worsen, a follow-up visit with your vet is necessary.

Your dog may need a different treatment approach, or your vet may need to diagnose and address a different underlying health issue that’s complicating their recovery.

Ringworm treatment typically lasts six weeks or more and requires repeated vet visits and testing.

If you need some help, then dog insurance can help cover these ongoing costs as long as the condition is not pre-existing.

It's one small step that can make a big difference in managing your pet’s health needs, whether they have ringworm or another condition.

Our Standard Care Pre-existing plan can cover recent conditions.

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Your ringworm questions, answered

What does ringworm look like on a dog?

Ringworm in dogs typically appears as circular or irregular patches of hair loss with scaly, crusty, or inflamed skin.

The patches may be red or grey and can appear anywhere on the body, though the face, ears, paws, and legs are most commonly affected.

Nails may become brittle or deformed. Thick fur can hide lesions, so look out for changes in coat quality or areas of broken hair as well as visible patches.

Is ringworm contagious from dogs to humans?

Yes. Ringworm is a zoonotic infection, meaning it can spread from dogs to people through direct contact with an infected dog or contaminated surfaces.

In humans, it typically appears as red, circular, itchy patches of skin. Infection is more serious in young children, elderly individuals, and anyone with a weakened immune system.

If you notice ringworm-like symptoms on your skin after contact with an infected dog, see your GP or pharmacist for advice.

How do vets diagnose ringworm in dogs?

Vets use several methods to confirm ringworm. A Wood's lamp (UV light) can cause some strains of the fungus to fluoresce, though not all types show up under UV light.

Microscopic examination of hair or skin samples can identify fungal spores. The most reliable method is a fungal culture, in which a sample is grown in a laboratory, though this can take up to 10 days to yield results.

Your vet may use one or a combination of these tests.

How is ringworm treated in dogs?

Treatment typically combines topical therapy — antifungal shampoos or creams applied directly to the skin — with oral antifungal medication prescribed by your vet.

Treatment courses usually last at least six weeks and should not be stopped early, even if symptoms appear to have cleared.

Your vet may perform follow-up fungal cultures to confirm the infection has been fully cleared before ending treatment.

How long does ringworm last in dogs?

With appropriate treatment, most dogs recover from ringworm within 6 to 12 weeks.

Dogs remain contagious for approximately three weeks after treatment begins. Without treatment, the infection can persist for longer and spread to other animals and people in the household.

Completing the full course of treatment as prescribed by your vet is essential.

How do I clean my home if my dog has ringworm?

Environmental decontamination is a critical part of treatment, as ringworm spores can survive on surfaces for up to two years.

Wash all bedding, towels, and soft furnishings on the hottest wash suitable for the fabric. Disinfect grooming tools, food bowls, and hard surfaces with a dilute bleach solution (1:10 bleach to water).

Vacuum carpets and soft furnishings regularly and dispose of vacuum bags immediately. Prevent your dog from sleeping on beds or sofas until the infection has cleared.

Can ringworm in dogs go away without treatment?

In mild cases, healthy dogs may eventually clear the infection without treatment, but this can take many weeks and is not recommended.

During this time, the infection is likely to spread to other areas of the body, other pets, and potentially to people in your household.

Prompt veterinary treatment is always advised to shorten the duration of the infection, reduce your dog's discomfort, and prevent transmission.

Does pet insurance cover ringworm treatment in dogs?

Ringworm treatment can be costly due to the length of treatment (often six weeks or more) and involves repeated vet visits, fungal culture testing, medicated shampoos, and oral antifungal medication.

As an illness, ringworm is typically covered by comprehensive dog insurance policies, provided it is not a pre-existing condition.