How do dogs get ringworm?

HotbotBy HotBotUpdated: July 4, 2024

Ringworm, despite its name, is not a worm but a fungal infection affecting the skin, hair, and nails. Scientifically known as dermatophytosis, ringworm can affect various animals, including dogs. Understanding how dogs get ringworm involves examining multiple factors, such as its causes, transmission methods, symptoms, and prevention strategies.

The Cause of Ringworm in Dogs

Ringworm is caused by a group of fungi called dermatophytes. The primary species responsible for this infection in dogs include Microsporum canis, Microsporum gypseum, and Trichophyton mentagrophytes. These fungi thrive in warm, moist environments and feed on keratin, a protein found in the outer layer of the skin, hair, and nails.

How Ringworm is Transmitted

Direct Contact

The most common way dogs contract ringworm is through direct contact with an infected animal. The fungal spores can be present on an infected dog's skin, hair, or nails. When another dog comes into contact with these spores, the fungi can transfer and begin to grow in the new host.

Indirect Contact

Ringworm can also be transmitted indirectly. Fungal spores can survive on various surfaces, such as bedding, grooming tools, and furniture, for extended periods. When a dog comes into contact with these contaminated objects, they can pick up the spores and develop an infection. This mode of transmission is particularly concerning in multi-pet households, shelters, and kennels.

Environmental Exposure

Environments that are warm and humid provide ideal conditions for the fungi to thrive. Dogs that spend a lot of time outdoors, especially in such climates, are at higher risk of encountering the spores. Soil can also harbor dermatophytes, and dogs that dig or roll in contaminated soil can become infected.

Factors Increasing Susceptibility


Puppies and older dogs are more susceptible to ringworm due to their weaker immune systems. Puppies' immune systems are still developing, while older dogs may have weakened immunity due to age-related changes or underlying health conditions.

Health Status

Dogs with compromised immune systems, whether due to illness, stress, or medications, are at a higher risk of contracting ringworm. Conditions like malnutrition, systemic diseases, and chronic infections can weaken a dog's defenses, making them more vulnerable to fungal infections.


Certain breeds, particularly those with long or dense coats like Yorkshire Terriers and Jack Russell Terriers, may be more prone to ringworm. The dense fur can create a humid environment close to the skin, which is conducive to fungal growth.

Symptoms of Ringworm in Dogs

Skin Lesions

The most noticeable symptom of ringworm is the appearance of circular, red, and scaly lesions on the skin. These lesions often have a raised edge and may be itchy. Hair loss around the affected area is also common, giving the lesions a characteristic ring-like appearance.

Brittle Nails

In some cases, ringworm can affect a dog's nails, making them brittle and prone to breaking. This symptom is less common but can indicate a more severe infection.

Generalized Itching

While localized lesions are typical, some dogs may experience generalized itching and discomfort. This can lead to excessive scratching, licking, and biting, which can further irritate the skin and exacerbate the infection.

Diagnosing Ringworm in Dogs

Wood's Lamp Examination

A common diagnostic tool for ringworm is a Wood's lamp, which emits ultraviolet light. Some species of dermatophytes, like Microsporum canis, fluoresce under this light, making them easier to detect. However, not all ringworm infections will fluoresce, so additional tests may be necessary.

Microscopic Examination

Veterinarians may take samples of hair, skin scrapings, or nail clippings from the affected area for microscopic examination. By looking for fungal spores and hyphae under a microscope, they can confirm the presence of ringworm.

Fungal Culture

A fungal culture is the most definitive method of diagnosing ringworm. Samples are placed in a special medium that encourages fungal growth. This process can take several days to weeks, but it helps identify the specific species of dermatophyte causing the infection.

Treating Ringworm in Dogs

Topical Treatments

Topical antifungal medications, such as creams, ointments, and shampoos, are commonly used to treat ringworm. These products help kill the fungi on the skin's surface and can alleviate symptoms. Regular bathing with medicated shampoo can also help reduce spore contamination.

Systemic Treatments

In more severe or widespread cases, systemic antifungal medications may be necessary. These drugs, such as itraconazole, terbinafine, or griseofulvin, are administered orally and work from within to combat the infection. Treatment duration can vary, often lasting several weeks to months.

Environmental Decontamination

To prevent reinfection and stop the spread of ringworm, thorough cleaning of the dog's environment is crucial. This includes washing bedding, disinfecting grooming tools, and cleaning surfaces with antifungal solutions. Frequent vacuuming can help remove fungal spores from carpets and upholstery.

Preventing Ringworm in Dogs

Regular Grooming

Maintaining good grooming habits can help prevent ringworm. Regular brushing removes loose hair and debris, reducing the likelihood of fungal spores settling on the skin. Regular bathing with antifungal or medicated shampoos can also be beneficial, especially for dogs prone to skin issues.

Limiting Exposure

Minimizing a dog's exposure to known sources of ringworm, such as infected animals and contaminated environments, can reduce the risk of infection. Avoiding contact with stray animals and ensuring your pet's living area is clean and dry are essential preventive measures.

Boosting Immune Health

Keeping your dog healthy and maintaining a strong immune system is key to preventing infections. Providing a balanced diet, regular exercise, and routine veterinary care can help ensure your dog's overall well-being and resilience against infections.

Understanding the Risks and Realities

While ringworm is a common and treatable condition, it requires vigilance to prevent and manage. Awareness of the causes, transmission methods, and preventive measures can help dog owners protect their pets from this bothersome infection. As we delve into the intricacies of how dogs get ringworm, it becomes clear that maintaining a clean environment, practicing good grooming habits, and ensuring overall health are fundamental steps in safeguarding our canine companions.

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