Mud fever (also known as cracked heels or greasy heels) is a condition of the skin on the lower legs which typically occurs during wet weather in horses who are turned out.
It is a bacterial infection caused by a particular bacteria called Dermatophilus. These bacteria live within the mud, with some fields being more severely infected than normal. The spores can persist for several years within the mud. The bacteria will not invade healthy skin, however skin which is constantly exposed to wet conditions will gradually become chapped and sore, allowing the bacteria to enter the skin and set up a localised infection.
Which horses are most severely affected?
Any horse can be affected by mud fever, it is certainly not a condition that is limited to those turned out in extreme muddy conditions. However those with fine limbs, ‘thin skinned’ breeds (such as Arabs and TBs) and those with white fetlocks and pasterns are generally most severely affected. Cobs with heavy feathers may suffer less due to the protection offered by the feathers.
How will I recognise if my horse has mud fever?
Typically the horse presents with scabs on the pasterns which cause the hair to clump together (has the appearance of a paintbrush). When these scabs are removed the skin underneath will have a layer of pus. Occasionally there will be swelling of the whole lower limb and in severe cases the horse may show signs of lameness. It is important not to confuse mud fever with leg mites, the latter normally cause scabs higher up the leg, with irritation and stamping of the legs a common feature.
How should I treat mud fever?
Early recognition and treatment is important to prevent the condition from progressing. In the initial stages the lower limb should be washed daily with an antibacterial shampoo (Malaseb or Hibiscrub solution work best). The legs should be dried well afterwards, ideally with paper towels which are disposed of afterwards- the scabs can remain infective for years in the environment so using the same towel to dry the legs daily will cause recurrence of infection. The legs should be clipped (with sedation if the horse is fractious or painful) and the scabs removed once they are softened. This stage is vital as the bacteria live under the scabs, so removal will allow the bacteria to be exposed to the antibacterial creams and shampoos. Dispose of the scabs carefully, they carry the mud fever bacteria! An antibacterial cream such as flamazine (prescription only) can be applied once the scabs are removed. Management at this stage is important, ideally the horse needs to be stabled in clean and dry environment. Continuing to turn the horse out when trying to manage mud fever almost always results in very slow improvement or sometimes deterioration. In the event of lameness or swelling the horse should be examined by a veterinary surgeon as may require antibiotics.
How can I prevent mud fever?
Once a horse has suffered from one bout of mud fever it is usually prone to future bouts, therefore, as with many things, prevention is better than cure! Removing mud from the horses legs is important, but hosing the legs creates a wet environment which allows the mud fever bacteria to flourish! Therefore the best way to remove mud is to allow the legs to dry and then to brush the mud away with a dandy brush. Covering legs to prevent mud fever can work but if the leg covers are not breathable then the warm, wet conditions will encourage bacterial growth. An oil based barrier cream such as Vaseline can be applied to legs before turn out. Placing rubber matting around water troughs and gateways can prevent severe muddy conditions from developing! Checking the horses legs on a daily basis can allow you to intervene and instigate treatment of mud fever at the first sign.