How to treat mud fever in horses?

Mud fever is the term given to a painful inflammatory condition involving the skin of the lower limbs although it can extend above the pasterns. It is one of a collection of diseases collectively referred to as pastern dermatitis. It is characterised by swelling redness of the skin pain which can be severe in addition to scabbing and crusting of the skin. Its more commonly found in white limbs and in heavily feathered breeds. 
What causes mud fever?
Causes of pastern dermatitis include but are not limited to bacterial infection fungal infection infestation with leg mites Chorioptes or harvest mites Neotrombicula autumnalis photosensitisation or autoimmune disease. In general when we refer to mud fever we are referring to the infection of the lower limbs with the bacteria Dermatophilus congolensis. Usually this gains entry to the skin through abrasions caused by trauma or by inflammation due to chronic wetting of the skin. 

How is it diagnosed?
As previously mentioned the clinical signs include pain and swelling of the lower limbs with one or more legs affected. Scabs are usually present as the disease becomes established. These scabs tend to come off with clumps of hair and can be associated with yellow oozing or crusting. Lameness can be mild to very severe and it can develop very quickly. 
In many cases your vet may diagnose and subsequently treat mud fever based on the clinical signs and history alone and resort to further testing in unusual or refractory cases. In these cases your vet will be able to carry out some tests such as culture or examination of swabs for bacteria or fungi skin scrapes biopsy or blood samples to determine the exact cause or the presence of any underlying pathologies. One example of an underlying condition is equine leukocytoclastic vasculitis best diagnosed by biopsy.
How is it treated?
It can be difficult to catch mud fever early. But careful investigation of your horses legs at least once a day will help to spot any signs. It can be difficult to perform a thorough check in the dark damp winter nights. But early diagnosis and prompt treatment will greatly improve success rates. 
In the first instance consult your vet who will confirm the diagnosis. They will be able to advise and start treatment as necessary. 
Changing the environment is the first and most important step
It is imperative that affected legs are kept clean and dry in order