Dermatophilosis is a major winter hazard for horses. It is an infectious disease caused by bacteria that are harboured within the scabs on the skin of infected horses and/or in the soil.
The name ‘mud fever’ has been adopted due to the fact that it is during prolonged periods of rain that the disease is most often seen. This is primarily because water has a softening effect on the skin that consequently becomes less effective as a mechanical barrier to infection, allowing the bacteria (Dermatophilus congolensis) to invade the skin.
Mud fever occurs on the limbs, most commonly around the coronet, pastern and fetlock, and most often on the white-haired pink-skinned areas. Once established, mud fever lesions can extend further up the limbs.
Lesions begin as weepy sores and develop scabs under which the bacteria live. In severe cases, areas may become swollen, pussy and bleed. The affected area is often very painful and the horse may even become lame.
In addition to wet muddy conditions, some horses are predisposed to mud fever, including those with heavy feathers around the legs. Horses with a concurrent illness may also be more prone to developing this and other conditions.
Diagnosis is generally based on clinical findings, but, if required, scabs can be examined under a microscope, or the area swabbed and cultured to rule out other bacterial causes.
Treatment is based around removing the scabs/crusts to expose bacteria to topical treatments and keeping the area affected dry.
If you are having trouble clearing up your horse’s mud fever, please call the clinic to arrange for a veterinarian to visit your horse. The earlier we can get on top of this condition, the greater the chance of a successful outcome.