Dermatophytosis in Dogs

icon May 11, 2023

What are Dermatophytosis?

Dermatophytosis is a fungal infection that affects the skin, hair, and nails of humans and animals. It is also commonly known as ringworm, even though it is not caused by a worm but by a group of fungi called dermatophytes. These fungi feed on the keratin in the skin, hair, and nails, and can cause a range of symptoms, from mild skin irritation to severe hair loss and scarring.

There are several species of dermatophytes that can cause dermatophytosis in humans and animals, but the most common ones are Trichophyton, Microsporum, and Epidermophyton. These fungi are contagious and can be transmitted through direct contact with an infected person or animal, or through contact with contaminated objects such as combs, brushes, and bedding.

Dermatophytosis can affect any part of the body, but it is most commonly found on the scalp, feet, and groin. In animals, it is most commonly found on the skin and hair of the face, ears, and paws. The infection typically presents as circular, red, scaly patches with a raised border and a clear center. The hair in the affected area may be brittle and break off easily, and the skin may be itchy and inflamed.

Symptoms of Dermatophytosis in Dogs

The symptoms of dermatophytosis in dogs can vary depending on the severity of the infection and the type of fungus involved, but here are some common signs to look out for:

  • Skin lesions

Ringworm can cause circular or irregular-shaped patches of hair loss with a crusty or scaly appearance. These lesions can be red and itchy, and they may appear anywhere on the body but are most commonly found on the head, ears, and limbs.

  • Dull or brittle coat

Dogs with ringworm may develop a dry or dull coat that is prone to breakage or shedding. In some cases, the fur may appear greasy or matted.

  • Itching

Ringworm can cause intense itching, which can lead to scratching and further skin damage. Some dogs may also develop secondary bacterial or yeast infections as a result of their scratching.

  • Nail abnormalities

In rare cases, ringworm can affect a dog's nails, causing them to become thickened, discolored, or brittle. This can be painful and may require medical treatment.

  • Swelling or inflammation

In severe cases, ringworm can cause the skin to become inflamed and swollen, with redness and tenderness around the affected area.

Case study: Dermatophytosis in a dog - IDEXX Canada

Causes of Dermatophytosis in Dogs

Dermatophytosis, commonly known as ringworm, in dogs, is caused by a fungal infection.

The most common fungal species that cause ringworm in dogs are:

  • Microsporum canis
  • Microsporum gypsum
  • Trichophyton mentagrophytes
  • Ringworm is highly contagious and can spread from one dog to another or from an infected animal to a human. 
    Dogs can contract ringworm through direct contact with an infected animal or object, such as bedding, grooming tools, or toys, that has been contaminated with the fungus. Ringworm spores can also survive in the environment for several months, increasing the risk of infection.
  • Factors that can increase a dog's risk of developing ringworm include poor hygiene, a weakened immune system, and living in crowded or unsanitary conditions.
  • Young puppies and dogs with long hair or thick coats are also more susceptible to ringworm because the fungus can thrive in warm and humid environments.

How Do You Treat Dermatophytosis in Dogs?

The treatment of dermatophytosis in dogs involves both topical and systemic therapy. 

Topical Therapy

Topical therapy includes medicated shampoos and sprays or ointments that contain antifungal agents such as ketoconazole, miconazole, and chlorhexidine. These shampoos should be used twice a week for at least four weeks or until the infection has cleared up. Medicated ointments and creams may also be prescribed for localized lesions.

Puainta™ Ringworm/fungal infection-Ointment

Systemic Therapy

Systemic therapy involves the use of oral antifungal medications such as griseofulvin, itraconazole, and terbinafine. These medications are usually given for several weeks to months and may require periodic monitoring of liver enzymes and kidney function.

Environmental Decontamination

In addition to medication, environmental decontamination is essential in preventing the spread of dermatophytosis. All bedding, grooming tools, and toys should be thoroughly cleaned and disinfected. Infected dogs should be isolated from other pets in the household until the infection has cleared up.

It is important to note that treatment for dermatophytosis can be lengthy and may require several weeks to months of therapy. It is also important to follow up with your veterinarian to ensure that the infection has been completely resolved and to monitor for any potential side effects of the medications used.

Is Dermatophytosis Contagious to Dogs?

Yes, dermatophytosis is a highly contagious fungal infection that can spread from one dog to another and even to humans. It is caused by fungi known as dermatophytes, which can survive in the environment for long periods. The most common way that dogs contract dermatophytosis is through direct contact with infected animals or contaminated objects such as grooming tools, bedding, or furniture. The infection can also spread through spores in the air, making it important to isolate infected dogs and disinfect their surroundings to prevent further spread of the disease.



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