How to treat mud fever in horses?

benefit from antibiotics but not all cases will be given antibiotics in the first instance. This decision will be made by your vet after a clinical examination. Some horses may benefit from topical steroid cream once the bacterial infection has resolved. 
In conclusion the main aim of treatment is to remove contaminated scabs and to keep the skin clean and dry 
Any underlying conditions such as mite infestation will also need to be treated. One recent small study found that topical treatment with essential fatty acids helped to reduce the severity but not prevent mud fever in a small select group of cases. This may form the basis for future research and development. 
Can it be prevented?
Ideally horses would be kept in clean and dry conditions to prevent this. However this is often not possible particularly during long spells of wet conditions and where grazing is limited leading to poaching of fields and gateways. 
If you do have to turn your horse out in muddy conditions rinsing the mud off may help. But care should be taken to dry the legs thoroughly. Use a clean towel that can be washed between uses to reduce reinfection. Some people will even use a hair dryer for this if the horse will tolerate it.
It may be advisable in healthy horses to let the mud dry onto the feathers or hair before brushing it off as this avoids chronic wetting of the skin which may increase the risk of mud fever developing. Some horses skin is particularly sensitive to repeated wetting so in these animals letting the mud dry is preferable. 
Commercially available dry boots can be helpful in some cases. But care must be taken to ensure that they are fitted properly as if not any loose dirt or grit will rub the legs. This can lead to abrasions which will allow bacterial infection to develop. 
To clip or not to clip? 
The feathers are evolved to protect a horses legs. But if they are constantly wet and mud laden they may exacerbate the problem. As a general rule if the skin on the legs is intact then the feathers may be useful in preventing disease. However if mud fever has set in clipping may help with treatment as it will improve the chances of keeping the skin dry.
Barrier creams can be helpful in some individual cases
However they can create a moist environment
in which bacteria can thrive. If you choose to use these they should only be applied to clean dry skin. And the cream should be removed regularly to ensure that the skin beneath remains healthy.