Mud Fever


Mud fever and rain scald are seasonal problems mostly over the winter caused by a bacterium that revels in the name Dermatophilus congolensis. The organism is persistent in the environment and lies dormant in a spore form until it is activated by damp weather. So the disease becomes apparent after heavy rainfall, when the skin can become soaked. With persistent wet weather the outer layers of the skin are softened and more easily damaged allowing the organism to penetrate through any mild traumatic damage. The organism then starts to multiply to establish the condition. Some horses seem more prone to suffering from mud fever than others. Hairy legs can protect against it by providing a further physical barrier against the bacteria, whereas horses with light coloured skin seem more susceptible.

Mud fever will start off on the underside of the pastern and fetlock. There is a sticky exudate, which mats the hair and forms dry crusts. Pick these off and the skin is raw and inflamed underneath. On occasions there can be a severe infection and reaction with noticeable swelling of the leg and associated lameness.

Rain scald appears on parts of the horse that are most exposed to rain – the back and neck. The condition appears as streaks where the rain runs off. The scabs are similar to those of mud fever with pus underneath the crusts.

Treatment of both diseases entails keeping the horse in a clean dry area where possible. Loose crusts can be picked off and the surrounding hair clipped. Embedded crusts can be soaked in an antiseptic wash of diluted Hibiscrub or pevidine. . The areas can then be cleaned twice daily with antiseptic wash, patted dry and then apply a wound cream. In severe cases oral antibiotic may be required.

Prevention is not easy. Ideally avoid too much contact with mud, but this is easier said than done. A water repellent barrier may be applied to the legs before the horse is turned out. After exercise allow the mud to dry off first and then brush off rather than soaking the leg with water to wash it off.


This information is provided for information purposes to our registered clients. It is the individual opinion of veterinary surgeons within the practice. It should not be relied upon as an alternative to a clinical examination and diagnosis by a veterinary surgeon. If in any doubt please contact the practice for further advice.

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