Mud Fever in Horses: Causes, Symptoms, and Care

Mud fever in horses is one of the most common — and most frustrating — skin conditions in British and South African yards. Scabby, weeping, cracked heels; hot, swollen lower legs; a horse that’s suddenly footy on concrete. By the time most owners notice, the infection is already established. This guide covers what mud fever actually is, how to recognise early signs, proven treatment protocols, and the stable-management changes that break the cycle for good.

What Is Mud Fever?

Mud fever is the common name for pastern dermatitis — a bacterial skin infection affecting the lower leg, most often the pastern, fetlock, and heel bulbs. It is caused primarily by Dermatophilus congolensis, the same organism responsible for rain scald on a horse’s back. Secondary invasion by Staphylococcus and Streptococcus species is common in more severe cases.

The bacteria live in soil and on the horse’s skin as harmless commensals. They only become infectious when the skin barrier fails — typically through prolonged wetting, mud chafing, or micro-abrasions. Once in, they multiply in the warm, damp, airless environment under scabs and between feathers.

Heavy-feathered breeds — Shires, Clydesdales, Gypsy Cobs, cobs, and native ponies — are especially prone, but any horse can get it.

Mud Fever Symptoms to Watch For

Early mud fever can be subtle. Run your hand down every leg every day during wet months — you’ll feel trouble before you see it. Classic signs:

• Small, hard, crusty scabs on the pastern, heel bulb, or back of the fetlock
• Matted hair over the scabs, often with yellow or greenish discharge underneath
• Hair loss when scabs are picked off, revealing raw pink skin
• Heat in the lower leg
• Swelling (filled legs), sometimes only on one leg
• Soreness on palpation — the horse may snatch the leg up
• Lameness, usually mild but occasionally severe
• Cracked heels in chronic cases, with deep fissures that bleed

In severe cases, the infection spreads up the cannon bone and becomes “cracked heels” plus full-blown cellulitis — a painful, hot, grossly swollen leg that’s a veterinary emergency, not a management problem. The same broken skin is also the commonest route by which lymphangitis takes hold in a hind leg, which carries a far stronger tendency to recur.

What Causes Mud Fever?

Mud fever isn’t really about mud — it’s about wet skin. Mud is just the most common culprit. The underlying cause is prolonged moisture on the pastern, which softens the skin, disrupts the protective lipid layer, and lets bacteria in. Common triggers:

• Standing in wet, muddy fields for 8+ hours a day
• Deep-litter beds or dirty bedding that stays damp
• Excessive hosing without proper drying afterwards
• Leg washing in winter — arguably the fastest way to cause it
• Sand schools — fine silica abrades the skin, even when dry
• Clipping too close over the pastern, removing natural protection
• Feathers trapping moisture against the skin in heavy breeds
• Photosensitivity on white legs — sunlight can damage unpigmented skin underneath wet mud

Horses with compromised immune systems — those with Cushing’s disease (PPID), poor nutrition, or on long-term corticosteroids — are at higher risk and heal more slowly.

How to Treat Mud Fever

The core principle: keep the skin dry and lift the scabs safely. The scabs trap bacteria against the skin. You cannot kill the infection without removing them, but you cannot rip them off aggressively or you’ll make the skin worse.

Step 1: Clip the Feathers

Carefully clip the feathers around the affected area with small trimmers. This exposes the scabs, lets air circulate, and makes cleaning manageable. Leave a safe margin of unaffected coat. For heavy-feathered breeds where owners want to preserve the feather for shows, at least trim around the scabs enough to see the skin.

Step 2: Soften and Remove the Scabs

Apply a warm salt-water wash or a dilute antiseptic solution (Hibiscrub 1:10 in warm water is the traditional vet choice). Soak a clean towel, hold it against the leg for 10–15 minutes, then gently lift the softened scabs away. Do not pull — if a scab isn’t ready, leave it and repeat the next day.

Step 3: Dry Thoroughly

This step is non-negotiable. After washing, pat completely dry with a clean towel. Blow-dry on a cool setting if needed. Any residual moisture defeats the entire exercise.

Step 4: Apply an Antibacterial Barrier Cream

Once the skin is clean and dry, apply a zinc-oxide-based barrier or a prescription topical antibiotic. Common choices:

• Sudocrem / nappy rash cream — zinc oxide base, mild, good for mild cases
• NAF Love the Skin He’s In mud fever cream
• Keratex Mud Shield Powder as a preventative
• Prescription flamazine (silver sulfadiazine) — vet-only, excellent for established cases
• Dermobion, Fuciderm — combined antibiotic and steroid creams, prescription only

Apply a thin layer, rub in gently, and let air get to the leg. Do not bandage unless specifically directed by a vet.

Step 5: Daily Reassessment

Check the legs every morning and evening. Gently remove any new scabs that have lifted, reapply cream, and keep the horse out of mud while it heals. Most mild cases resolve in 10–14 days. Chronic cases or those with cellulitis need veterinary input.

When to Call the Vet

Do not self-treat if you see any of the following. Call the vet promptly:

• Sudden severe lameness
• Hot, swollen leg that feels “tight” and is clearly painful
• The horse is off his food or dull
• Thick yellow or green pus discharge
• Raised temperature (above 38.5°C)
• Swelling tracking up the leg toward the hock or knee
• Mud fever that hasn’t improved after 10 days of home treatment

Cellulitis can cause permanent damage to the lymphatics of the lower leg and needs systemic antibiotics and, often, anti-inflammatories. Don’t leave it.

Preventing Mud Fever: The Winter Management Plan

Prevention is infinitely easier than cure. Build these into your winter routine:

Turnout Management

• Rotate poached gateways — move the electric-fenced gap every few weeks
• Use hardcore, matting, or woodchip around water troughs and feed areas
• Consider restricted turnout on a dry pad during the wettest weeks
• Check the field drainage — chronic mud fever often has a drainage fix

Daily Leg Checks

• Feel every leg morning and evening — you’re checking for heat and small scabs
• In white-legged horses, watch for pink, inflamed skin under the hair — a pre-mud-fever warning
• If the horse comes in caked, brush off once the mud is dry rather than hosing — dry dirt rubs off; wet mud soaks in

Barrier Products

Apply a pig-oil-and-sulphur mix, commercial mud fever cream, or Keratex Mud Shield to the pasterns before turnout. This repels water and prevents bacterial colonisation. Reapply after each wash or every 2–3 days in severe weather.

Don’t Wash Unless You Can Dry

The single biggest mistake British yards make is hosing muddy legs at night and then rugging and stabling without drying. If you must wash:

• Use warm water, not cold
• Pat dry with absorbent towels
• Stable in a clean, dry bed with no deep-litter dampness
• Consider a boot-dryer or hairdryer for the pasterns

Mud Fever Boots

Turnout boots designed to keep mud off the pastern (e.g. Equilibrium Stretch & Flex Flatwork Wraps, Premier Equine Mud Fever Boots) work well for at-risk horses. They need to be checked and cleaned daily — a damp, dirty boot causes exactly what you’re trying to prevent.

Mud Fever in Heavy Breeds and Feathered Cobs

Feathered breeds deserve a word on their own. The feather traps moisture and warmth right against the skin — a perfect incubator for Dermatophilus. For working Cobs, Clydesdales, and Shires, winter management should include:

• Weekly feather checks — part the hair and inspect the skin underneath
• Consider trimming feathers shorter for winter, even if it hurts show appearances
• Dress feathers with a pig-oil blend weekly
• Treat any small scab immediately before it becomes an infection

Chronic Progressive Lymphoedema (CPL), a genetic condition affecting feathered breeds, can mimic or worsen mud fever. If a Cob’s lower legs stay chronically thickened and scaly even in summer, ask your vet about CPL — the management is different.

Nutrition and Mud Fever

Skin health starts in the feed bucket. Horses on a balanced diet with adequate trace minerals, essential fatty acids, and vitamin E are far more resistant to skin infections. Key nutrients:

• Zinc and copper — skin integrity and wound healing
• Omega-3 fatty acids — reduce skin inflammation. Linseed or fish oil
• Vitamin E — antioxidant; supports skin repair
• Biotin — horn and skin quality

A horse on ad-lib hay and a broad-spectrum balancer (e.g. Baileys Lo-Cal Balancer, Saracen Equi-Jewel, Spillers Original Balancer) should be adequately supplied. Horses on straight feeds alone often aren’t.

Myths About Mud Fever

• “Only horses in muddy fields get mud fever.” False. Stabled horses on deep litter get it too.
• “You need antibiotics to cure it.” Most mild cases resolve with good skin management alone.
• “White legs are the problem.” White skin is slightly more prone to photosensitivity reactions, but the cause is still bacterial, not pigment.
• “Scrubbing scabs off is the best treatment.” Aggressive removal damages the skin and worsens the infection.
• “Once you’ve had it, it’ll come back.” Only if the underlying management isn’t fixed.

Frequently Asked Questions

How long does mud fever take to heal?

Mild cases usually clear in 10–14 days with good management. Chronic or infected cases can take 4–6 weeks, and recurrent mud fever in heavy-feathered breeds may need ongoing management through every wet season.

Can I ride a horse with mud fever?

Mild cases, yes — light hacking on dry ground is fine, and movement helps reduce leg filling. Avoid wet grass, deep going, and schooling that will irritate the skin. If the horse is lame or the leg is hot and swollen, stop riding and call the vet.

What is the best cream for mud fever?

There isn’t one “best” product. Mild cases respond to a simple zinc-oxide barrier cream (Sudocrem). Moderate cases benefit from a proper equine mud fever cream (NAF, Keratex). Severe or non-responsive cases need a prescription product like flamazine or Dermobion from your vet.

Can mud fever spread between horses?

Yes, but indirectly. The bacteria spread via shared brushes, boots, towels, and tack. Disinfect grooming kit and don’t share boots between horses during an outbreak.

Does pig oil really work?

Yes, as a preventative. Pig oil (or a pig-oil-and-sulphur mix) creates a water-repellent barrier over the skin. It’s cheap, traditional, and effective. It is not a cure — it won’t clear established mud fever, but it does stop it starting.

The Bottom Line on Mud Fever

Mud fever is preventable with thoughtful winter management and curable in almost every case with patience and the right routine. The yards that consistently avoid it are the ones that keep legs dry, check them twice daily, clip feathers when necessary, and treat every small scab immediately rather than waiting to “see how it goes.” Do that, and even your heavy-feathered Cob can come through a wet British winter with clean, healthy pasterns.

For further reading, see the British Horse Society and British Equine Veterinary Association, or explore our guides to horse care and rain scald, its close cousin on the back and hindquarters.