Mud fever: recognising the symptoms

Mud fever on the rear of the pasterns

Mud fever — also known as greasy heel or cracked heels — is a bacterial infection caused by the organism called dermatophilus congolensis (dermatophilus means ‘skin-loving’).

The bacteria survive from year to year in the soil of pasture, with the spores often lying dormant during the summer months, only to be activated by the mild, wet winter conditions in which they thrive.

Healthy skin is able to resist these bacteria, but this resistance is often compromised by the abrasive action of rain and mud. Dry, chapped or sore skin allows bacteria to penetrate, resulting in infection. Any break in the skin, such as a small cut or graze, can also provide the organism with a means of entry.

Mud fever is characterised by matted hair, dry crusts and weeping sores, which ooze yellow-green serum. The condition usually affects the back of pasterns and fetlocks, although it can spread up the limbs and even across the belly. When it occurs on the back and quarters, the condition is referred to as rain scald or dermatophilosis.

Guide to mud fever symptoms

Severity Mild
Symptoms Redness around the heels, possibly some hair loss and inflammation
Treatment Wash the area with a mild solution of detergent (for example, Hibiscrub diluted 1:40) and dry thoroughly. Apply an anti-bacterial barrier cream, especially if the horse is to be turned back out into muddy conditions. Horses’ legs should be kept clean and dry to prevent a recurrence (wash horses’ legs with cold water only, because warm water opens pores and increases the chances of infection).
Severity Moderate
Symptoms Cracked heels, oozing scabs, matted hair
Treatment Ideally, the horse should be stabled during treatment. Wash and dry legs as above. Dry scabs should not be forcibly removed as this will be painful and expose the wounds to further infection. Applying creams with emollient properties will soften the skin, loosen scabs naturally and help to prevent further cracking. An ointment with anti-bacterial properties should be applied topically to attack the infection. Barrier creams should be applied if horse needs to be turned out.
Severity Severe
Symptoms Advanced build up of scabs, swollen legs, heat in the leg, pronounced lameness, the horse may appear to be uncharacteristically listless
Treatment Treat as for moderate and contact your vet, as intra-muscular administration of antibiotics may be necessary
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