A condition that the horse owner can be forgiven for confusing with mud fever is leucocytoclastic vasculitis. Although not as common as heel mange it is seen frequently by vets. It affects only white parts of the lower limb and usually the outside and is most often seen in Arabs or Arab crosses. Although superficially it looks like mud fever it is not caused by infection but is the result of a dysfunction in the local immune system. No amount of creams or lotions will help and it is only treatable with high doses of steroids given orally, often for several months. Fortunately, unlike mud fever, once cured it rarely recurs.
This horse looked as if it had a small patch of what appeared to be mud fever. This had failed to response to many months of treatment by the owner. When the hair was clipped away a very large area of skin damage could be seen. This is not in fact mud fever, it is a specific condition called leucocytoclastic vasculitis. It can be cured but requires prolonged veterinary treatment.
This horse had had these painful swollen areas on the outside of its pastern and above its fetlock for several months. The owner had tried every cream known to mankind to get rid of them thinking that it was mud fever. This is another case of leucocytoclastic vasculitis and after veterinary treatment and a course of steroids the skin condition fully resolved.