Ringworm in Dogs: Symptoms, Treatment, and Prevention

Updated: June 13, 2023


Ringworm is a common fungal infection that can affect dogs, causing discomfort and potentially spreading to other pets and even humans. Despite its name, ringworm is not caused by a worm but by various species of fungi, most commonly Microsporum canis. It manifests as circular patches of hair loss on the dog’s skin, often accompanied by redness, itching, and scaling.

One of the primary symptoms of ringworm in dogs is the appearance of circular lesions with a raised, scaly border. The center of the lesion may appear crusty or scabbed, and hair loss is commonly observed within the affected area. Dogs with ringworm may also experience intense itching, leading to excessive scratching, which can further aggravate the condition. In severe cases, multiple lesions may develop, and the infection can spread to different parts of the body.

Treating ringworm in dogs typically involves a multifaceted approach. Firstly, it is essential to isolate the infected dog to prevent the spread of the fungus to other animals and humans. Medications, such as antifungal creams or ointments, are commonly prescribed to treat the infection topically. In more severe cases or when the infection is widespread, oral antifungal medications may be necessary. Additionally, medicated shampoos or dips can help kill the fungi and soothe the affected skin.

Preventing ringworm in dogs involves maintaining good hygiene practices. Regular bathing with a mild antifungal shampoo can help reduce the risk of infection. It is crucial to keep the dog’s living environment clean and free from contaminated bedding, brushes, or other grooming tools. If a dog comes into contact with an infected animal, thorough cleaning and disinfection of the living area are necessary to minimize the chances of the fungus spreading.

What is ringworm?

Ringworm is a fungal infection that affects the skin, hair, and nails of both humans and animals. Despite its name, it has nothing to do with worms and the infected areas may not always appear as rings.

The term “ringworm” originated from the characteristic round, red, raised rings that often mark the boundaries of the inflamed lesions seen in human cases. However, this term can be misleading as the infection can take different forms in different individuals.

The fungal pathogens responsible for ringworm infections are a group of fungi called dermatophytes. Dermatophytosis is the medical term for this condition. There are various species of dermatophytes, each with its own characteristics. Some species are specific to certain animals, meaning they only infect one species. On the other hand, some dermatophytes can be transmitted between different species of animals, including humans.

Ringworm in Dogs:

Infections can occur in various domesticated animals, including dogs, cats, horses, and even livestock. Humans can also contract ringworm from infected animals or through direct contact with contaminated objects or surfaces. It is important to note that not all animals or humans exposed to dermatophytes will develop an infection. Factors such as the individual’s immune system and the virulence of the fungus play a role in determining susceptibility.

Ringworm infections present with a range of symptoms, including redness, itching, scaling, and hair loss. The appearance of the lesions can vary, with some individuals developing the classic ring-shaped pattern while others may have different shapes or even a diffuse rash.

How is ringworm transmitted?

Ringworm is a highly contagious fungal infection that spreads through direct contact with the fungus. Transmission can occur by coming into contact with an infected animal or person, as well as by touching contaminated objects or surfaces. The fungus responsible for ringworm produces spores that can survive for extended periods of time, remaining dormant on various items for up to 18 months. Common sources of contamination include combs, brushes, food bowls, furniture, bedding, carpets, and other environmental surfaces.

However, it is important to note that not every contact with the ringworm fungus will result in an infection. The likelihood of developing an infection depends on several factors. One crucial aspect is the degree of environmental contamination. If the fungus is present in high concentrations, the risk of infection increases significantly. On the other hand, if the fungal spores are present in small amounts, the chance of contracting the infection is relatively low.

Another factor that influences susceptibility to ringworm is the age of the exposed individual. Young animals, including puppies, kittens, and immunocompromised individuals, are more vulnerable to infection. Their developing immune systems may not be as effective in warding off the fungal invasion, making them more prone to contracting ringworm.

How is ringworm in dogs treated?

The treatment of ringworm in dogs typically involves a combination of topical and systemic therapy, along with thorough environmental cleaning. Topical therapy involves the application of creams, ointments, or shampoos to the affected areas of the dog’s skin. These products may contain anti-fungal agents such as miconazole, terbinafine, or clotrimazole. Additionally, medicated shampoos or lime-sulfur dips can be used to aid in the treatment. Shaving the hair in the affected areas may also be recommended by the veterinarian to facilitate topical treatment.

However, topical therapy alone may not be sufficient, and oral anti-fungal drugs are often prescribed for more effective treatment. Griseofulvin has been commonly used, but newer drugs like itraconazole or terbinafine are now preferred due to their reduced side effects. The duration of oral treatment can vary, but it generally lasts for a minimum of six weeks, and sometimes longer therapy may be necessary.

Ringworm in Dogs:

It is crucial to continue the treatment as prescribed by the veterinarian and not stop prematurely. Discontinuing treatment too soon can lead to a recurrence of the infection. Periodic ringworm cultures may be taken to assess the progress of the treatment and determine if the dog is still infected.

In households with multiple pets, it is advisable to separate the infected animals from the non-infected ones and focus on treating the affected pets. However, depending on the circumstances, treating all the pets in the household may be recommended by the veterinarian.

Environmental cleaning plays a significant role in preventing the spread and recurrence of ringworm. Infected hairs contain fungal spores that can contaminate the environment. Regularly cleaning and disinfecting the living areas, including floors, furniture, and bedding, is important. It is also crucial to remove pet hair, as it may harbor fungal spores. Restricting the infected dog to easily cleanable rooms can be helpful in reducing environmental contamination.

What is the risk to humans?

Ringworm is highly transmissible to humans, particularly young children, and it is crucial to take necessary precautions to minimize exposure to the fungus during the dog’s treatment. Individuals with compromised immune systems are more susceptible to contracting and displaying clinical signs of ringworm. If anyone in the household develops skin lesions characterized by small patches of thickened and reddened skin with raised scaly edges, immediate medical attention should be sought. Fortunately, ringworm in humans typically responds well to treatment.

It is important to note that the ringworm fungus can remain infectious in the environment for up to 18 months, increasing the risk of reinfection. Therefore, when handling infected animals, it is essential to wear gloves as a protective measure. Afterward, thorough handwashing should be practiced to remove any potential fungal spores.

In order to minimize the risk of transmission to humans, several additional precautions should be taken. Regularly cleaning and disinfecting the living environment, including surfaces, furniture, and pet bedding, can help reduce the presence of fungal spores. Vacuuming the house frequently, using a vacuum cleaner with a high-efficiency particulate air (HEPA) filter, can effectively remove spores from carpets and upholstery. It is also advisable to wash any potentially contaminated items, such as combs, brushes, and clothing, in hot water with appropriate disinfectants.

How long will my dog be contagious?

When aggressive treatment is employed, infected pets typically remain contagious for approximately three weeks. However, if minimal measures are taken or if the prescribed approach is not followed diligently, the ringworm infection can persist for a longer duration, prolonging its contagiousness. It is crucial to comply with the recommended treatment plan to ensure effective resolution of the infection.

During the contagious period, it is advisable to minimize exposure of the infected dog to other dogs, cats, and family members. This reduces the risk of spreading the infection to others. Maintaining proper hygiene practices, such as frequent handwashing and regular cleaning of the living environment, is also essential in preventing the transmission of the fungus.

Monitoring the progress of the treatment is vital. Two consecutive negative fungal cultures indicate successful treatment of the dog. These cultures are typically taken periodically to assess the presence of the fungus and evaluate the effectiveness of the prescribed treatment. It is important to continue the treatment until the veterinarian confirms that the infection is fully resolved and the dog is no longer contagious.

What does ringworm in dogs look like?

Ringworm lesions in dogs typically manifest as circular areas of hair loss, known as alopecia. As these circular lesions grow larger, the central area may heal, and hair can start to regrow in the middle of the lesion. The affected hair strands are delicate and prone to breakage. While these lesions are generally not itchy, they may occasionally become inflamed and develop a scabby covering. Multiple patches of hair loss can be scattered throughout the dog’s body in most cases. In some instances, fungal infections may also affect the dog’s nails, resulting in rough, brittle, and broken claws.

Ringworm in Dogs:

It is important to note that some dogs can carry ringworm fungi in their hair or skin without exhibiting any visible signs of the disease. These dogs, despite not having apparent skin lesions, can still transmit ringworm to other animals or humans. Therefore, it is crucial to be cautious and take preventive measures even when an infected dog appears asymptomatic.

Will my dog recover from a ringworm infection?

With proper treatment, most dogs can recover from a ringworm infection. However, it is important to follow the prescribed treatment plan diligently. If the treatment is discontinued prematurely or if it is not sufficiently aggressive (such as using only topical treatment), there is a risk of symptom recurrence. Additionally, if the dog has an underlying health condition that compromises its immune system, it may be more susceptible to recurring symptoms.

In some cases, despite receiving appropriate treatment, the ringworm infection may persist. When this happens, it may be necessary for the veterinarian to explore alternative anti-fungal drugs. These alternative treatments aim to address the infection more effectively and increase the chances of successful resolution.

It is important to work closely with your veterinarian throughout the treatment process and follow their guidance. They will monitor the progress of the infection and make adjustments to the treatment plan as needed. By staying committed to the prescribed treatment and maintaining good communication with your veterinarian, the likelihood of a full recovery from ringworm can be maximized.

Is it contagious?

Ringworm in dogs, similar to humans, can be transmitted through direct contact. However, it’s important to note that certain types of ringworm may be species-specific, meaning they are not contagious between different species. On the other hand, some types of ringworm can be transmitted across species.

The high level of contagiousness of ringworm is due to its ability to survive on various surfaces and be easily transmitted. “Ringworm is very contagious because the infection can spread not only from infected animal to animal but also through objects contaminated by an animal or human with ringworm,” explains Dr. Brian Evans, a veterinarian at Dutch. Moreover, the fungus responsible for ringworm can survive on untreated surfaces for up to 18 months. To prevent reinfection, it is crucial to thoroughly clean all contaminated objects using a disinfectant.

Ringworm in Dogs:

Fungal spores, which cause ringworm, can adhere to objects such as dog brushes, combs, food and water bowls, furniture, carpets, and bedding. Eliminating ringworm spores from the environment can be challenging. However, several measures can be taken to minimize their presence. Regular vacuuming, particularly with a vacuum cleaner equipped with a high-efficiency particulate air (HEPA) filter, can help remove spores from carpets and other surfaces. Steam cleaning carpets can also aid in killing the fungus. Additionally, washing affected laundry items twice and using a diluted bleach solution on surfaces can be effective in reducing contamination.

How is a ringworm infection diagnosed?

In certain cases of canine ringworm, a diagnostic technique involves examining the skin and coat under a Wood’s lamp, a special ultraviolet lamp that emits a specific wavelength of light. When observed in a dark room, some cases of ringworm may exhibit a yellow-green fluorescence. However, it is important to note that not all cases will display clear fluorescence, and certain species of dermatophytes, the fungi responsible for ringworm, may not fluoresce under a Wood’s lamp. Therefore, additional diagnostic methods may be required to confirm the presence of ringworm fungi.

The most reliable and accurate method for diagnosing ringworm in dogs is through fungal culture in a laboratory setting. This involves obtaining samples of hair and skin scrapings from the affected areas of the dog. These samples are then processed and cultured to promote the growth of any present fungi. While some positive cultures can be confirmed within a couple of days, there are instances where the fungal spores may require more time to grow, resulting in a longer waiting period of up to three weeks for culture results.

Culturing the fungus provides a definitive confirmation of ringworm infection and allows for the identification of the specific species of dermatophyte involved. This information is crucial for determining the most effective treatment approach. It also helps to differentiate ringworm from other skin conditions that may present with similar symptoms.

While a Wood’s lamp examination can provide a preliminary indication of ringworm through fluorescence, it is not always definitive. To obtain a conclusive diagnosis, a fungal culture is the preferred diagnostic method. This allows for accurate identification of the fungi involved and guides the appropriate treatment course.

How to treat ringworm in dogs

If you suspect that your dog has ringworm, it is highly recommended to seek veterinary attention and initiate appropriate treatment rather than adopting a wait-and-see approach. Dr. Brian Evans advises, “There is a chance that ringworm can resolve spontaneously, but this will come at the expense of your dog’s well-being. They will experience symptoms for a longer duration than necessary if they do not receive proper medical care.” Untreated ringworm in dogs can persist for nine to 12 months, causing prolonged discomfort for your pet. Considering that ringworm is contagious to both humans and other animals, relying on the infection to resolve on its own over such an extended period is not a favorable strategy.

By promptly addressing the issue and obtaining professional medical care, you can alleviate your dog’s discomfort and prevent the spread of the infection to other household members or pets. Effective treatment can significantly reduce the duration of symptoms and improve your dog’s overall well-being. Additionally, early intervention can help minimize the risk of reinfection and prevent the infection from becoming more severe.


Ringworm is a common fungal infection that can affect dogs. While the name “ringworm” may be misleading as it is not caused by a worm, it can still cause significant discomfort and health issues for our furry companions. It is important to be aware of the symptoms, such as circular areas of hair loss and brittle nails, and seek veterinary attention if you suspect your dog has ringworm.

Treatment for ringworm typically involves a combination of topical and systemic therapies, with the goal of eliminating the fungal infection and preventing its spread. Topical creams, ointments, shampoos, and dips are commonly used to treat affected areas, while oral antifungal medications may also be prescribed for more severe cases. It is essential to follow the prescribed treatment regimen and complete the full course of medication to ensure effective eradication of the infection.

Preventing the spread of ringworm is crucial, as it can be transmitted between animals and humans. Taking precautions such as keeping infected pets separate from healthy ones, practicing good hygiene, and regularly disinfecting the environment can help minimize the risk of transmission.



Paula patton is an avid dog lover and pet enthusiast with a wealth of knowledge in pet food and treatment. With her vast experience, she has gained valuable insights into the world of pets and their needs. Through her writings, Paula shares her expertise, helping fellow pet owners make informed decisions for their furry companions. Her passion for animals shines through every word, making her a trusted source for all things related to pets.

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