Rain Scald & Mud Fever

Kate Hore RNutr(Animal). Snr Nutritionist at NAF

Mud Fever is a bacterial infection of the skin around the lower leg and fetlock caused by the bacterium, Dermatophillus congolensis. It may also be seen across the back, neck and head, where it is referred to as Rain Scald. Ordinarily the bacteria originate from the soil, and can live happily on skin without any issue. However any break in the skin allows the bacteria to enter then dermatitis sets in, meaning Mud Fever typically occurs in heel cracks, while Rain Scald is most likely where the skin has been damaged, for example by insects or injury. Signs include itching, matter hair and hair loss, leading to inflammation and painful scabs which can result in lameness. Prolonged wetting from muddy conditions in the field can weaken skin allowing entry; but so too can abrasive bedding, and any minor nicks and cuts. Check legs daily and quickly treat any minor abrasion with wound cream and an effective barrier cream.

While it can be seen in any animal, those with thin skin and white legs do seem to be particularly prone. Bacteria particularly proliferate in warm, wet conditions, so while feathers may help protect from mud, once infection sets in they can encourage it by keeping the area warm and wet. Similarly the warm summer showers can encourage Rain Scald, as it both benefits the bacterial growth, but also allows spread of infection by flies and ticks.

Treatment of either removes removal of the scabs – but carefully. Never pick off dry, hard scabs as this leaves an open wound allowing bacteria in, and is likely to be painful for the horse and, therefore, potentially dangerous for you! Wash the area with a mild shampoo, and it is advised to choose one which is naturally anti-bacterial; massage in well and leave for ten minutes before rinsing with clean water. For persistent scabs apply a cleansing solution and poultice overnight, which should soften the scabs making them easier to remove.

Once the scabs are removed and the area cleaned, ensure the area is carefully dried using paper towelling or clean, dry towels. Avoid re-using the same towel, or sharing between horses, as this could potentially spread infection. It is also advised to separate infected animals from others, to stop the spread of infection; and it may be useful to stable them in dry, well-ventilated boxes, out of the rain which will stop the bacteria from growing.

While tackling what’s happening on the surface, check your horse’s diet to ensure you are promoting strong, healthy skin from the inside out through a fully balanced diet and, if required, specific targeted nutrition.

To prevent further attack, ensure the affected areas are clean and dry, and liberally apply a suitable barrier cream before turnout or exercise. Don’t forget to also regularly apply an effective fly repellent, to prevent vector-borne spread of infection by insects. Opinions are divided as to whether to wash legs when they come back in or not. It is thought that both wetting and chilling are key triggers, so if you do wash legs regularly ensure they’re thoroughly dried too.

Typically Rain Scald and Mud Fever respond well to appropriate treatment and management by the owner, particularly over summer when they tend to be less severe. If they persist talk to your veterinary surgeon, as there may be a secondary infection which needs professional treatment.