Rain Scald Versus Mud Fever: Distinguishing Two Common Horse Skin Conditions

Rain scald and mud fever are distinct but related skin conditions caused by Dermatophilus congolensis — correct identification guides effective welfare treatment.

Key Facts

• Rain scald affects the back and hindquarters; mud fever (pastern dermatitis) affects the lower legs
• Both are caused by Dermatophilus congolensis bacteria but in different anatomical locations
• Rain scald is promoted by prolonged wetting of the coat from rain exposure
• Mud fever is promoted by prolonged moisture contact from mud and wet ground
• Both conditions cause matted crusts, hair loss, and painful raw skin underneath

Welfare Considerations

Rain scald and mud fever cause the same welfare harm through different routes: the Dermatophilus bacteria penetrate moisture-softened skin, causing painful crusting lesions that, when removed, leave raw, tender skin. The distinction matters for treatment and prevention: rain scald requires weatherproof rugs and drying of the back and hindquarters; mud fever requires dry standing areas, barrier creams, and access to hard standing away from mud. Both conditions cause discomfort at grooming and saddling, behavioral changes including resistance to being handled, and in severe cases, secondary infection requiring antibiotic treatment. Prevention through housing management and appropriate rugging prevents most welfare harm from both conditions.

What You Can Do

• Provide weatherproof shelter for all horses during prolonged wet weather
• Use appropriate waterproof rugs to protect the back and hindquarters from rain scald
• Provide hard standing or dry areas away from mud for horses prone to mud fever
• Soften crusts with dilute chlorhexidine shampoo before removal to minimize pain
• Apply barrier creams to clean, dry lower legs before turnout in muddy conditions