Mud Fever – What is it?

What is Mud Fever?

Mud Fever, also known as greasy heel or dermatophilosis, is a skin infection caused by Dermatophilous congolensis – a micro-organism that is best described as a cross between a bacteria and a fungus. The organism is a normal inhabitant of the skin of horses. For an infection to occur, two predisposing factors must be present:

- Persistent moisture on the skin

- Damage to the skin

Un-pigmented skin (white socks) are more susceptible to mud fever because of the damaging effect of solar dermatitis.   Rain Scald is another name given to an infection by the same organism where the lesions are distributed over the body, neck and head.

What are the characteristic signs of Mud Fever?

The infection is characterized by crust (scab) formation with or without swelling of the surrounding area. The crusts characteristically adhere to clumps of hair so when they are removed, the matted hairs come with them. Often the skin below is inflamed and oozes serum. There is usually swelling of the pastern and lameness may be a feature.

How is Mud Fever best treated?

Dermatophilous congonlensis is susceptible to most of the commonly used anti-bacterial agents. Because it lives on the skin underneath the matted crusts, it is important that these are first removed. This process can be uncomfortable for a horse, so it helps to first soften them with warm soapy water, Fungal Cleansing Shampoo is ideal to use.

Once removed the skin should be washed with an appropriate anti-bacterial agent such as Betadine or Reynards Antibacterial Wash as it contains Chlorhexidine, known to kill dermatophilious, and leave for five to ten minutes.  A small, soft bristled nail brush is ideal for this as it works the active cleansing agent down into the skin. Once this has been completed, the area should be rinsed and dried thoroughly with a clean towel.

An antibacterial ointment such as Equifix Skin Repair can then be applied. Your veterinarian can advise you – corticosteriods are often used in combination with the antibacterials – if there is moderate or severe skin inflammation.  It should be noted that if the skin is cracked corticosteriods may delay healing, therefore their use is questionable. Systemic antibiotics are indicated if the lesions are initially too painful to treat as described, or if there is pronounced swelling involving two or more legs.

Can Mud Fever be Prevented?

Because the organism is a normal inhabitant of horse’s skin and because wet grass and mud provide the persistent moisture for an infection to start, it is difficult to completely prevent Mud Fever. It is possible however, to reduce both the chances of a horse getting the disease and the severity of the symptoms by making sure the heels and pasterns are cleaned and dried thoroughly after exercise.

A useful preventative remedy involves spraying the area with a 50:50 mixture of baby oil and vinegar after drying. The baby oil prevents the skin from cracking while the vinegar, which is acidic, alters the pH of the skin enough to make conditions inhospitable for the organism to grow.   Other preparations like Equifix Repair Cream which has emu oil with mild antiseptic properties can also be used at this time.

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