Ringworm in dogs

Everything You Need to Know About Ringworm in Dogs

Skin disease is very common in dogs. Among these skin problems, infections are considered to be the most common. Skin infections in dogs are caused by either a bacterial or fungal microorganism. A common fungal infection that is often seen in dogs is ringworm, or more technically known as dermatophytosis. Keep reading to learn more about ringworm in dogs, including symptoms, treatment, and prevention.

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Causes of Ringworm Infection in Dogs

Ringworm, or more formally known as dermatophytosis, is a type of fungal infection in dogs that affects the skin, hair, and nailbeds. This type of infection is caused by a group of fungal organisms called dermatophytes. Dermatophytes are comprised of 3 fungal species, Microsporum canis which accounts for about 70% of all dermatophytosis cases in dogs, Microsporum gypsum causing around 20% of dermatophytosis reports, and Trichophyton metagrophytes which is responsible for 10% of the reported cases.

These organisms grow and proliferate on the outer layers of the skin, and occasionally on nail beds and hair follicles. They mostly grow on dead skin cells and the keratin component of the skin, which is abundant on the topmost layer and near the dog’s nails. The proliferation and growth of these dermatophytes often stop when they reach healthy cells and tissues in the skin, but it usually takes a couple of weeks before the infection stops on its own.

These dermatophytes not only affect dogs but can also cause skin problems in cats, rabbits, and humans. They are considered zoonotic, a term used for infectious organisms that can be transferred from animals to humans and vice versa.

How did my dog get ringworm?

Direct contact is the main mode of transmission of ringworm among dogs and in between dogs and other animals. Transmission often happens when a dog is in contact with the infected animal or any contaminated object like a carpet, food bowl, or bedding. Infected animals spread fungal spores into the environment when they shed off infected hair. Fungal spores can stay viable for up to 18 months.

However, contact alone is not enough to cause an infection in dogs and humans. Host factors like immunity, age, health condition, nutrition, and grooming behavior can influence and affect the risk of infection even with direct contact with the fungal spores. Also, infected animals that have recovered can develop some degree of resistance against dermatophytes that protect them against reinfection for a short time.

Symptoms of Ringworm Infection in Dogs

Dermatophytosis in dogs typically causes hair loss and itchiness. Lesions are often seen in bald patches, and the skin can become scaly and produce dandruff. The skin can also become darker and occasionally red from inflammation. Secondary bacterial infection may occur on the affected parts of the skin and pustular nodules may start to develop.

The commonly affected parts of the dog’s body are the feet, face, ears, and tail, as these are the ones that come in contact with various objects in the environment or other animals. The nails and nailbeds can also become infected, which can result in misshapen, broken, or brittle nails in dogs. Redness and darkly pigmented skin are often seen in dogs with ringworm infection on their nails and nailbeds.

Dogs can become carriers of dermatophytes, and not show any signs even if they are carrying the fungal organism. Asymptomatic carriers can still transfer the infection to other animals and humans through contact.

How is ringworm diagnosed in dogs?

Ringworm in dogs is diagnosed by inspecting a sample of affected hair under the microscope. The presence of fungal spores on the hair sample, along with clinical signs and physical examination, are often enough for your vet to arrive at a tentative diagnosis and start treatment.

Some types of ringworm fluoresce under UV light and can be easily detected with the use of a Wood’s lamp. Fluorescence of a dog’s skin and hair is indicative of dermatophytosis in canines. A positive fungal culture, isolation, and identification are needed for a definitive diagnosis. But for most cases, a tentative diagnosis is enough reason to start treating an infected dog for ringworm.

Treatment Options for Ringworm Infection in Dogs

In some cases of ringworm in dogs, the infection can be self-limiting and resolves on its own. As mentioned, the presence of spores of the fungus is not enough to cause infection, and the host’s immune system and health condition influence the ringworm infection. Improving the health condition and balancing the dog’s immune system can help treat ringworm infection.

In most cases, an antifungal medication is needed to treat ringworm infection. Topical antifungal treatments, such as shampoos and creams are often enough to control and treat ringworm in dogs. Treatment can last for weeks and an extension is recommended even after skin lesions have resolved.

In severe cases of ringworm infection, oral antifungal medications may be indicated and prescribed by your vet. This is usually done as a last resort if topical treatment is ineffective because prolonged use of oral antifungal medications can have potential liver side effects. In any case, it’s best to visit your vet if you suspect that your dog may have a ringworm infection.

Can ringworm infection be prevented?

Since ringworm is primarily transmitted through direct contact, isolation of the infected animal and daily cleaning of the house and objects that might have come in contact with an infected animal can help prevent transmission and control the spread of ringworm. Supplements that help improve your dog’s immune system and general health can help prevent infection even if there’s contact with infectious spores.

Recently, a vaccine is being studied that can offer protection against some species of dermatophytes that cause ringworm in dogs. Having your dog vaccinated can help offer protection but does not eliminate the risk entirely, since other fungal species can cause skin infection in dogs.

Read more:

Common Skin Parasites in Dogs

How to Prevent Ear Infection in Dogs

Dog Allergy Remedies

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