Mud fever is a common winter ailment and is caused by a bacterium that is found in the soil and thrives in wet conditions known as dermatophilus congolensis. The bacterium penetrates chapped, damaged or softened skin in horses resulting in weepy sores, scabs and in severe cases swelling and lameness.
Mud fever is more common during the wet winter months and occurs mostly around the coronet, heels and pastern in horses but can also occur higher on the leg or even belly. Horses or ponies with heavy feather on the leg can be particularly prone to mud fever as the hair becomes covered in wet mud and legs remain damp and horses with white legs and pink skin are also more prone to mud fever.
The first symptoms of mud fever are a mud rash on the backs of pasterns or fetlocks. This can then develop into sore, crusty skin, matted hair and weepy sores. In serious cases the leg can become hot and swollen and the bacteria may penetrate the skin causing a deeper infection that requires antibiotic treatment.
There are number of ways that mud fever can be prevented. Nutritional supplements designed to promote skin and coat health may help in preventing skin from cracking and allowing mud fever infection developing and supplements designed to support the immune system may help the horse to fight any mud fever infection. Clipping feathered legs can help the horse’s wet legs to dry quicker and prevent mud fever developing, whilst equine chaps or leg wraps that cover the lower leg and pasterns can be worn when the horse is turned out to protect the legs from mud. Bringing a horse in periodically and allowing the legs to dry completely and brushing of all mud and applying barrier creams or mud repellents to clean dry legs, before turning out in wet weather can also help to prevent the occurrence of mud fever. However, barrier creams are best applied before mud fever develops, as if applied after mud fever occurs, they can trap the infection and moisture in, and prevent damp legs from drying out.
Should mud fever develop there are a number of mud fever treatments available. However, before applying any mud fever treatment legs should be cleaned thoroughly and scabs softened with an antibacterial solution such as Hibiscrub, then the legs rinsed and dried thoroughly. Ideally the horse should be removed from the muddy conditions. This is best done by keeping the horse in a dry, clean stable during treatment but for horses at grass with no access to a stable it may only be possible to move them to a less muddy field or prevent them accessing the muddiest areas of the field (usually gateways) by fencing the area off with some temporary fencing.
Mud fever treatments containing zinc, castor oil, lead acetate and anti-inflammatory ointments can all help to treat mud fever effectively but in severe cases of mud fever where the leg has swollen antibiotic treatment may be needed. Once the mud fever has been treated the skin may remain tender for a while after and applying a soothing cream such as zinc or castor oil can ease this.