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Ringworm in Dogs

Ringworm or dermatophytosis is one of the contagious skin infections that is pretty common amongst dogs, and in animals in general. It’s caused by a fungus that breaks down keratin contained in hair, skin, and claws. Despite the fact that this is not a deadly disease, it can be uncomfortable for the dog and not very appealing to the eye. Ringworm usually appears as a round, reddish patch without hair on various places from nose and belly to paws. But in some cases, it can cause scales and crusts on the skin. The treatment of ringworm can be long and tedious, but one should stay persistent for successful results. Since this is a disease that can spread to humans and other pets throughout direct contact or contaminated surfaces, it’s important to pay attention to general hygiene and to cleaning places the infected dog resided. In this article we will go into detail about the prevention through good hygiene and how to treat this disease effectively.

What Does Ringworm Look Like on a Dog

Ringworm on a dog's noseRingworm on a dog can appear very similar to other skin diseases dogs can get. There are several ways ringworm can manifest, since ringworms eat the keratin from which the skin, hair and nails are built. But in dogs, it’s mostly the hair follicle that becomes infected.

Some dogs develop dandruff and/or spots of hair loss (round patches) with dry, crusty skin, while in others, reddish lesions can be detected. The affected areas on the body in most cases are not itchy, but there are circumstances where those lesions get inflamed and where scabs can form. In some cases, ringworm can also be asymptomatic. This can be a problem in an environment with more animals present since they can still act as carriers of the disease.

Is Ringworm Contagious?

Ringworm is highly contagious. It can be spread from dogs to owners very easily, as well as to other humans. People can get ringworm from their dogs through direct contact or through contaminated surfaces where dogs leave the fungi spores behind, such as on places they slept, the carpet, couch, clothes, etc. One more reason to be more cautious and to pay more attention to hygiene and to wash hands and clean surfaces is the fact that the fungi spores can survive 12- 20 months in favorable environments. 1

It’s more likely for a human to get infected with ringworm if he has wounds, scratches or other micro lesions on the skin. Or in other cases, if the immune system is weakened. Thus people with chronic diseases, children and older people are more susceptible to catching the fungus.

Unlike in dogs, ringworms in humans can be rather itchy. They appear as a characteristic circular red shape on the skin. The disease goes by several names in human “dermatophytosis” or “tinea.”

Treatment in humans depends on the location the ringworm emerges. If it appears somewhere on the skin, it can be treated with antifungal creams, powders or lotions. But in another case, when the ringworm appears on the scalp, usually it’s necessary to visit a doctor. A more precise treatment must be determined since it’s a more delicate place of infection.

All other domestic animals can get ringworm as well. This should also be kept in mind when the dog is diagnosed with this fungus. To remove all the spores the dog has perhaps left behind, every spot the dog resided should be cleaned and disinfected thoroughly.

Symptoms of Ringworm in Dogs

Dog Ringworm SkinDespite the fact that ringworm is not a life-threatening disease, the easy spreading to humans and other animals should be considered and kept in mind. So what are the things one should look for when suspecting the dog has gotten ringworm? First, the period after infection until the development of first signs can take from 7 to 14 days.

Usually, in the early stages, as the infection starts developing, there are circular areas without hair (alopecia) present. As the process continues, the central area starts to heal, making it look like a patch. In general, the quality of the hair may deteriorate; it becomes brittle and dry. The skin as well can become inflamed and scabby. But in most cases, the lesions are not itchy. Depending on the area the infection took place, claws can also be affected, so they start to become brittle and rough.

It’s not always the case that you notice the characteristic circular patches. In some conditions, there can be seen scales of skin like dandruff, scabs, or even darkened skin (hyperpigmentation). When some of these signs are noticed, a trip to the veterinary clinic for further consulting is recommended.

How Do Dogs Get Ringworm?

For a dog to get ringworm, he must come into direct contact with the fungus, either directly in contact with other dogs or indirectly by coming in contact with the contaminated environment (sleeping in the bed or using the same brush as an infected dog).

Ringworm in Puppies

Even though dogs of all ages can get the ringworm, puppies, older dogs and dogs with lesions on the skin or with weaker immunity are more susceptible to the infection. Unlike in adult dogs, puppies don’t necessarily develop the usual ring areas of hair loss. There are bald patches with dandruff, crusts, and broken and brittle hair all over the body. While usually in dogs the affected areas are not itchy, puppies can more often develop itchiness. So, unlike in older dogs there are more cases where itchiness is present as well. Diagnosis and treatment of ringworm in puppies is the same as in older dogs.

Diagnosis of Ringworm in Dogs

The first thing the veterinarian will do is perform a physical examination of the dog’s body. If he finds an indication that the dog has ringworm (patches with dry, scaly skin and fur), further diagnostic methods will be conducted.

Usually, the first one to be used is a method that involves the use of a Wood´s lamp, where the fungi fluoresce under the ultraviolet light of the lamp. This method is not fully reliable since a false positive can occur, so it’s mostly used as a screening method.

Microscopic examination is conducted by taking the skin scraping or hair from places where it fluoresces under the Wood’s lamp.

But the most reliable method is growing a fungal culture from samples of skin scrapings or plucked hair. The results can be seen in a couple of days, but in some cases, the final diagnosis results can be prolonged for up to a month.

Since there are various similar skin diseases, the veterinarian could carry out other diagnostic procedures to rule out those potential diseases as well.

Ringworm Treatment for Dogs

After the ringworm has been diagnosed, proper treatment will be determined. The treatment method will depend on the affected area, the severity of the infection, and the symptoms manifested.

There are three different treatment methods: topical, oral therapy and environmental decontamination. Usually, a combination of all of them is needed for successful results in the end.

Topical Therapy for Ringworm in Dogs

Topical treatment is used to prevent the spread of fungus spores into the environment so owners and other animals that come in contact with the dog aren’t affected. Treated with topical therapy, the fungus spores are directly killed, so even if they end up spreading into the environment, they are not infectious.

The most common products used are shampoos, lotions, and ointments that mostly contain either Miconazole or Clotrimazol. Miconazole is usually combined with Chlorhexidine, because in this combination, the results are most efficient.

Oral Therapy for Ringworm in Dogs

With the topical treatment getting rid of the worms already existing on the surface, oral therapy gets to the core of the problem and prevents the fungus from further spread and reproduction. Itraconazole and Terbinafine are options mostly used by veterinarians. The treatment should be continued until the dog tests negative.

Environmental Decontamination

Environmental decontamination is also an important part of ringworm therapy. Improving the conditions where the dog resides can be of great benefit, but there are not many products that are effective. The one that works on 80% ringworm spores is bleach (diluted 1:10). It is effective on any surface that can be bleached. Before bleaching, it’s important to do general cleaning from vacuuming carpets to washing surfaces with soap and detergent, since bleach does not work if there is any dirt present.

Home Remedies for Ringworm in Dogs

There are some home remedies for ringworm in dogs people reach out for instead of conventional therapy. The five most used are apple cider vinegar, oregano oil, lemongrass essential oil, neem oil, and garlic.

These remedies are applied topically to the affected area on the skin. They should be applied several times a day (usually 3-4 times) to have an effect. But, please be informed about the detailed instructions on how to use these remedies, since some of them should be diluted before being used.

Before trying out these unconventional methods, it’s always better for you to consult with your veterinarian.

Untreated Ringworm in Dogs

Treating ringworm can take time, since fungus in general can be very tedious to treat. But one must remain persistent since untreated ringworm can spread to larger areas of the body, provoking even more damage to hair, skin and nails. Also, the possibility of causing infections in humans and other animals becomes even higher.

How to Prevent Ringworm in Dogs?

Given that there is no way to prevent the dog from getting ringworm on the outside, the things that can help to minimize the possibility of getting the infection include cleaning the places where the dog sleeps, cleaning the grooming brush regularly, and vacuuming to remove hair and skin cells.


As with any other fungal infections, ringworm can become tiresome and repetitive since it can take a long time for it to be fully cured. Causing round patches of hair loss, this fungal infection is not life-threatening, but it can be very uncomfortable. The high potential to spread to humans and other pets should be kept in mind. Thus, the treatment must be conducted properly with all caution possible. Combining topical and oral treatment together with environmental decontamination is the key for a successful treatment. Cleaning and keeping good hygiene of your dog and the environment is the best prevention for this disease.

Frequently Asked Questions (FAQs) about Ringworm in Dogs

What Causes Ringworm in Dogs?

Ringworm in dogs is caused by various types of fungus, also known as dermatophytes. Since they use keratin as their food, and hair, skin and claws contain keratin, these areas are usually affected.

How Do You Know If Your Dog Has Ringworm?

If you notice round patches of hair loss (alopecia) or broken hair and scaly skin, it’s an indication for you to visit a veterinarian who will further conduct diagnostic methods that will determine if the dog is in fact infected with ringworm or if the reason is another infectious agent.

How to Treat Ringworm in Dogs?

After the diagnosis has been set, the veterinarian will recommend the proper treatment method according to the severity of infection, the environment where the pet resides and other pets and people in their surroundings, as well as their general health status and susceptibility to infection. The treatment method will depend on the affected area, the severity of the infection and symptoms manifested. For successful results, a combination of topical, systematic and environmental treatment methods is needed – all recommended by your veterinarian.

How Long Does Ringworm Last in a Dog?

The treatment can be long, repetitive and tiring. It can take up to six weeks for a dog to heal completely, and sometimes even longer, depending on the severity of infection and the intensity of treatment conducted. For a dog to be fully marked as cured and the treatment to be stopped, two negative ringworm cultures are required.

How Contagious Is Ringworm from Dog to Human?

Ringworm is highly contagious, and it can be spread by direct contact with infected animals or contaminated things and surfaces such as dog bedding, furniture or grooming tools. It’s more likely for a human to get ringworm if there are any wounds present on the skin or if their general immunity is compromised.

How Long Is Ringworm Contagious in Dogs?

When the treatment is being conducted rigorously and intensively, the contagious period will last about three weeks. If there are any obstacles for doing the treatment properly, the contagious period will also be prolonged for a longer period of time. But the spores themselves can stay contagious from 12-20 months on surfaces and things.

Dr. Iman Krijestorac (DVM)
Dr. Iman is a young, ambitious veterinarian working in a small animal vet station while volunteering in the local Dog shelter. Zoonotic and infectious diseases are one of her major interests, together with dog nutrition and diet for which she visited several seminars and conferences. She has always had a heart for big dogs, she has an old Appenzeller Sennenhund going by the name "Yoda".

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