What Mud Fever Really Is

Mud fever – also called pastern dermatitis or, in its hind-leg form, cracked heels – is a bacterial skin infection that takes hold when the skin of the lower leg is repeatedly wet, muddy and compromised. The usual culprit is Dermatophilus congolensis, a bacterium that lies dormant on the skin and only becomes a problem when conditions allow it to multiply. Prolonged wetting softens and damages the skin barrier, mud abrades it further, and the bacteria walk straight in.

Wet winters are the perfect storm. Fields that never drain, gateways churned into knee-deep slurry, and horses stood in the rain for hours all mean the legs are rarely dry. Once infection sets in, you'll typically see matted hair, scabs, crusty patches and swollen heels, and in more serious cases heat, pain and lameness. It is far easier to prevent than to treat, which is why a consistent daily routine through the winter months pays for itself many times over.

Spotting the Early Warning Signs

Mud fever rarely appears overnight. If you run your hands down your horse's legs every day – which you should be doing anyway – you'll notice changes well before they become dramatic. Look and feel for:

• Small, gritty scabs on the heels, pasterns or the back of the cannon bone
• Hair standing up or clumping together in tufts
• Patchy hair loss, or skin that looks red and angry underneath
• Mild swelling of the lower leg, or heat in the pastern
• Sensitivity when you touch the area, or a reluctance to pick the foot up

Catch it at the scabby-tuft stage and you can usually manage it yourself within a week or two. Leave it until the leg is swollen, hot and painful and you're looking at a veterinary visit, possibly antibiotics, and a horse on box rest. If the leg is significantly swollen, the horse is lame, or the scabs are spreading upwards, ring your vet rather than persisting with home treatment.

Keep Legs Clean and Dry

The single most effective thing you can do is reduce the amount of time your horse's legs spend wet. This is about management as much as grooming.

• Manage the mud itself. Gateways and trough areas are where mud fever starts. Put down mats, hardcore or bark chippings, or fence off the worst boggy patches so horses aren't forced to stand in standing water.
• Rotate turnout. Splitting a field into sections and resting the wettest parts gives the ground a chance to recover and gives the legs a chance to dry.
• Bring in for a few hours. Even a short spell on clean, dry bedding each day allows the skin to dry properly. This matters more than most owners realise.
• Dry, don't scrub. When your horse comes in, towel-dry the legs with a clean cloth, or use paper towel on the very muddy bits. Work downwards, and use a separate cloth per leg to avoid spreading bacteria from one leg to another.
• Keep bedding clean. Deep, dry shavings or straw are ideal. Wet, soiled bedding simply recreates the field conditions indoors.

Barrier Creams: Use Them Wisely

Barrier creams are a genuine help, but only if used correctly. The principle is simple: you want a protective layer between the skin and the mud. You do not want to seal mud, moisture or bacteria against the skin.

Apply a barrier to clean, completely dry legs before turnout. Good options include zinc oxide-based creams and ointments, castor oil-based preparations, or a simple petroleum jelly layer for horses with sensitive skin. Pay particular attention to the heels, the pastern and the back of the fetlock – the areas that get splashed first.

Where a horse is already prone to mud fever, some owners find a sulphur-based barrier helpful, but always patch-test on a small area first, and never apply a barrier over broken, scabby or weeping skin without veterinary advice. Reapply every day in wet weather; a barrier that has worn off is doing nothing at all.

Why Aggressive Washing Makes Things Worse

It feels counter-intuitive, but hosing mud off every evening is often the very thing that keeps mud fever going. Every wash adds moisture to skin that is already struggling, strips the natural oils that form the skin's own waterproof barrier, and if you scrub at scabs you create fresh wounds for bacteria to enter.

If you must wash – for example, before applying a treatment – use lukewarm water, a mild antibacterial shampoo, and keep it brief. Then dry the leg thoroughly, towel first and let the air finish the job. Avoid cold hosing in winter unless your vet has advised it for another reason.

Whatever you do, do not pick scabs off. Soften them with an antibacterial cream or a warm poultice and let them lift naturally over several days. Picking leaves raw skin that will crust over harder within 48 hours and sets your recovery back a week.

Building a Winter Routine That Holds Up

Prevention comes down to consistency rather than any single product. Check legs daily with your hands, not just your eyes. Keep the driest turnout you can manage, dry legs properly when they come in, apply a barrier before they go back out, and resist the urge to over-wash.

For horses with feathering, clipping the lower legs in autumn can make an enormous difference – it's far easier to keep a clipped leg clean and dry, and you'll spot problems early. If your horse has had mud fever before, start your barrier routine in October rather than waiting for the first scab of December. A little daily attention now saves a lot of frustration – and a lot of veterinary bills – later in the season.