Dermatophytosis Tinea Capitis (Fungal Skin Infection, Ringworm) in Dogs

  • Occurrence: common
  • Location of illness: Skin/Fur
Content
Download/Print

Dermatophytosis, also known as tinea capitis or ringworm, is a fungal infection of the skin that occurs in dogs and is caused by dermatophytes, a group of fungi. This infection typically affects the superficial layers of the skin, as well as hair and sometimes claws.

The most important facts at a glance

Dermatophytosis, also known as ringworm, is a fungal infection in dogs caused by specialized fungi that can break down keratin. The most common pathogens include the fungal genera Microsporum and Trichophyton. Transmission usually occurs through direct contact with infected animals or contaminated objects. Fungi can survive in the environment for months, increasing the risk of infection. Dogs with weakened immune systems or young dogs are particularly susceptible to infection.

Typical symptoms include circular hair loss, dry skin, itching, and poor coat quality. Diagnosis is often made by clinical examination and analysis of hair and skin scales under a microscope. A culture of skin samples can also be performed to identify the fungus. Antifungal shampoos or creams, as well as systemic antifungals, are often used for treatment. Treatment often lasts several weeks to ensure that the infection is completely eliminated.

The prognosis for dogs with dermatophytosis is generally good, especially with early diagnosis and treatment. Prevention includes minimizing contact with infected animals and regularly disinfecting objects. A balanced diet and veterinary check-ups can strengthen the immune system and reduce the risk of infection. Newly adopted animals should initially be quarantined and examined for signs of the disease.

Causes

Dermatophytes are specialized fungi that can break down keratin, the main protein in skin and hair. The three main genera of these fungi are Trichophyton, Microsporum, and Epidermophyton. In dogs, Microsporum canis, Microsporum gypseum, and Trichophyton mentagrophytes are the most common pathogens.

These fungi are able to survive and multiply in keratinized tissues. Transmission usually occurs through direct contact with infected animals or contaminated objects such as brushes, combs, bedding, or even furniture. Dermatophytes can remain viable in the environment for months, increasing the risk of infection.

Another factor that can contribute to infection is the dog’s immune system. Dogs with weakened immune systems, whether due to illness, stress, or inadequate nutrition, are more susceptible to dermatophytosis. Young dogs are also particularly at risk due to their not yet fully developed immune defenses.

Symptoms

The symptoms of dermatophytosis in dogs can vary depending on the severity of the infection. The disease often begins with small, circular, hairless spots on the skin, known as classic “ringworm”. These lesions can expand and increase in number.

Affected skin areas may be reddened, scaly, or crusted. In some cases, pustules or blisters may also develop. The itching can vary greatly; some dogs show little sign of itching, while others scratch intensely.

In severe cases, the claws can also be affected, leading to thickening and deformation. With systemic spread, other areas of the body such as the head or limbs can also be affected.

Diagnosis

The diagnosis of dermatophytosis often begins with a thorough clinical examination and anamnesis. The veterinarian will ask about possible contact with infected animals or contaminated environments.

A common diagnostic method is to examine the hair and skin scales under a microscope for fungal spores and hyphae. Another method is to culture skin samples on a special nutrient medium to allow the growth and identification of the fungi. However, this can take several weeks.

A Wood’s lamp, which emits ultraviolet light, can also be used to identify affected hairs, as some dermatophytes fluoresce. However, not all pathogens are visible under a Wood’s lamp.

Therapy

Treatment of dermatophytosis in dogs usually involves a combination of topical and systemic antifungals. Topical treatments such as antifungal shampoos or creams are often used to reduce the number of fungi on the skin.

In severe or widespread cases, systemic antifungals may be required. These medications are administered orally and help fight the fungus throughout the body. Commonly used medications include griseofulvin, itraconazole, and terbinafine.

Treatment often needs to be continued for several weeks, even if symptoms subside, to ensure the infection is completely eliminated. Regular monitoring by the veterinarian is important to assess the progress of treatment.

Prognosis and follow-up care

The prognosis for dogs with dermatophytosis is generally good, especially if the infection is diagnosed and treated early. Most dogs respond well to treatment and recover completely.

In cases where the infection is not treated in time or in dogs with weakened immune systems, recovery may take longer and complications may occur. However, a full recovery is possible with proper treatment and care.

Prevention

The prevention of dermatophytosis in dogs involves minimizing contact with infected animals and contaminated environments. Regular hygiene practices, such as cleaning and disinfecting dog beds, brushes, and other items, can help reduce the risk of infection.

Strengthening the immune system through a balanced diet and regular veterinary check-ups can also help reduce the risk of infection. In the event of an outbreak in a multi-pet household, each animal should be checked for infection and treated if necessary to prevent spread.

It is also important to initially quarantine newly adopted or purchased animals and examine them for signs of dermatophytosis before they are brought into contact with other animals.

Content
Download/Print