Temperamental Victorian weather provides quite a few issues for both horses and their
owners. One of the more frustrating problems the presents during the wet winter months is
pastern dermatitis or commonly known as mud fever, greasy heel and other colloquial
The condition is usually caused by a bacteria called Dermatophilus congolensis although
other bacteria, fungi and yeasts do contribute. This same bacteria also causes rain scald
along the horses back and rump. Many bacteria live on normal healthy equine skin and will
cause an opportunistic infection when the skin becomes traumatized. Wet sandy paddocks
are ideal conditions for this to occur but can happen whenever the pasterns receive
abrasions and are left wet for too long such as frequently working in a sandy arena,
excessively washing the legs without drying and ill fitting boots.
It usually starts with generalised swelling of the affected area, redness and inflammation
and scaling of the skin. This then progresses on to moistness, matting of the hair and
scabbing or crusting. These scabs are painful, often located in the horizontal folds behind
the pastern and harbour the offending bacteria beneath. Swelling of the lower limb is
common as well as some degree of lameness in the more severe cases.
Pastern dermatitis usually affects the hind limbs and will often have a predilection for
unpigmented skin. Feathering on the legs of some breeds may provide a warmer and more
moist environment that the bacteria likes to grow in but these horses might also have an
infestation of mites that cause itching and the horse may eventually self traumatize.
There is no universal cure for mud fever as there may be a variety of microorganisms
present as well as other concurrent conditions. In uncomplicated scenarios, removing the
horse from wet pasture is the first step and ensuring they are on non irritating footing and
Horses with heavy feather may need them removed partially to access the lesions
but clipping horses with pastern dermatitis down to the skin is not recommended as the
clipper rash will provide bacteria with an opportunity to invade the deeper layers of the
The main principle of treatment of treatment is washing with a dilute solution of
chlorhexidine for example, removing any scabs that come away easily and drying the leg
extremely well. Use clean towels and a hair dryer can help ensure the leg is fully dry. Only
wash the legs every 2-3 days but apply topical antibiotic ointments daily e.g. dermapred or
Some horses may require pain relief if the heels are particularly cracker and some
advanced cases may become systemically ill or develop a cellulitis which require antibiotics.
Be aware that a handful of other conditions may resemble or predispose to mud fever and
these should be considered in particularly stubborn cases. For example, photosensitization
from being exposed to certain plants or drugs or liver damage often presents as sunburnt
crusts on white areas of the body. Some immune mediated conditions can cause similar
If you have any further questions please get in touch with any of our vets.
You can call our office on 03 5975 6586