Skin fungus in horses - Overview

Skin fungus in horses – recognition, prevention and treatment

Dermatophytosis is one of the most common skin diseases in horses. Although fungal infections are generally not life-threatening, they can cause significant skin problems and impair the animal's well-being. Furthermore, they are often contagious, requiring prompt diagnosis and treatment to prevent spread.

In this blog post, we want to provide a detailed overview of dermatitis in horses. We'll discuss the causes, symptoms, diagnosis, and treatment, as well as provide tips for prevention to keep your horses healthy.

What is skin fungus in horses?

Skin fungus in horses is often caused by various fungal species of the genus Trichophyton or Microsporum . These fungi live in the upper layers of the skin and feed on keratin, a protein found in the skin, hooves, and hair. Skin fungus is usually a contact-transmitted disease, meaning horses can become infected through direct contact with an infected animal or through contaminated objects such as grooming equipment, blankets, or feeders.

Skin fungus occurs primarily in warm, humid environments where the fungi find optimal growth conditions. The disease can occur in all age groups, but young horses and horses with weakened immune systems are more commonly affected.

Causes of skin fungus

Skin fungus is caused by infection with dermatophyte fungi. These fungi live not only on the surface of the skin but can also penetrate the hair follicles and deeper layers of the skin. The main causes include:

• Contact with infected animals : The most common route of transmission is contact with other horses that carry the fungus but do not show any noticeable symptoms (carrier animals).

• Inadequate hygiene and care : Especially in stables with high animal density and poor ventilation, fungal spores can easily get onto the floor or other surfaces, making infection more likely.

• Humid, warm climate : Fungi thrive in humid and warm environments. High humidity and warmth favor fungal growth, especially in the summer months.

• Weak immune system : Horses with a weakened immune system – due to other diseases, stress or poor nutrition – are more susceptible to fungal infections.

• Inadequate stable hygiene and poor ventilation : Inadequate ventilation in stables and lack of cleaning increase the likelihood of skin fungus, as the spores can survive and spread in humid environments.

Symptoms of skin fungus

Skin fungus can manifest in a variety of ways, depending on the type of fungus and the severity of the infection. Symptoms can appear in a single area or across the horse's entire body.

Typical symptoms of skin fungus are:

• Round, bald patches : The most noticeable symptoms include round, often scaly, bald patches that can appear on various parts of the body. The head, neck, and limbs are commonly affected.

• Redness and inflammation : The skin in the affected areas may appear reddish and inflamed. In some cases, scaly crusts may also form.

• Itching : The horse may scratch or rub itself more frequently in the affected areas. Itching is a common symptom that can make the horse restless.

• Hair loss : Hair loss occurs in the affected areas, resulting in bald patches and sometimes cracked patches. In widespread infections, this can affect the entire area.

• Changes in the coat : The skin may appear oily or dry, and the coat is often dull and brittle.

• Enlargement of the affected areas : If the infection is not treated, the affected areas may become larger and spread further.

Diagnosis of skin fungus

The diagnosis of dermatitis in horses should always be performed by a veterinarian, as many skin diseases can have similar symptoms. The veterinarian will typically perform the following diagnostic steps:

• Clinical examination : The veterinarian will carefully examine the affected areas of the horse and look for typical skin changes such as hair loss, scaling and inflammation.

• Fungal culture : A fungal culture is the most common method for diagnosing skin fungus. A skin swab is taken and examined for fungal spores. This provides more detailed information about the pathogen.

• Wood's lamp : A Wood's lamp can help to visualize the affected areas of some fungi because the fungal spores glow under UV light.

• Skin biopsy : In some cases, a small skin sample is taken to confirm the diagnosis, especially if another skin condition is suspected.

Treatment of skin fungus

Treatment for dermatitis in horses can vary depending on the severity of the infection. The goal is to kill the fungal spores, heal the affected skin, and prevent spread to other animals.

Treatment options include:

• Antifungal shampoos and ointments : There are various antifungal shampoos and ointments used to treat skin fungus in horses. These often contain active ingredients such as miconazole , ketoconazole , or itraconazole , which kill the fungi.

• Oral medication : In severe cases or with widespread infections, the veterinarian may also prescribe antifungal tablets for the horse to take orally.

• Baths and washes : The horse can be washed regularly with special antifungal baths to cleanse the skin and combat the fungal infection. Make sure all affected areas are washed thoroughly.

• Isolation and hygiene : Infected horses should be isolated from the rest of the herd to prevent the spread of fungal spores. The stable and all used equipment, such as grooming equipment and blankets, should be regularly disinfected and washed.

• Airy stable conditions and dryness : Since fungi thrive in moist, warm conditions, the stable should be well ventilated and cleaned regularly to prevent the development and spread of fungal infections.

Prevention of skin fungus

There are various measures that can help prevent fungal skin infections:

• Good stable hygiene : Keep the stable clean and dry. Avoid standing water and ensure adequate ventilation to ensure optimal air circulation and allow moisture to escape quickly.

• Regular disinfection of equipment : Grooming equipment, blankets and other equipment used by the horse should be disinfected regularly to kill fungal spores.

• Isolation of infected animals : Infected horses should be isolated immediately to prevent infection of other animals. This should be strictly observed, especially in larger farms or stables.

• Strengthening the immune system : A balanced diet, regular exercise and general care help to strengthen the horse's immune system and reduce the risk of fungal infections.

• Regular skin checks : Make sure to check your horse regularly for skin changes, especially during the summer months when fungal infections are more common.

Skin fungus is a common but treatable skin disease in horses. Prompt diagnosis and targeted treatment are essential to contain the infection and prevent it from spreading. With appropriate hygiene measures and good stable care, the risk of skin fungus can be significantly reduced. If you suspect skin fungus in your horse, it is advisable to consult a veterinarian promptly to ensure the best possible treatment.

Source: Martina Hemm April 2025