Pastern Dermatitis (Mud Fever)
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
Pastern dermatitis is a reaction pattern affecting skin at the back and sides of the pastern rather than one specific disease. Moisture and mud can soften the barrier and permit infection, but mites, Dermatophilus bacteria, staphylococci, dermatophytes, contact irritants, photosensitisation, immune-mediated disease and chronic progressive lymphoedema can create similar crusting lesions. “Mud fever” therefore describes context, not a complete diagnosis.
Early skin becomes red, tender and swollen, then develops greasy exudate, crusts and painful fissures. Hair mats or falls out. Severe inflammation extends up the limb, causes marked lameness, cellulitis or lymphangitis and can produce proliferative nodules. Dense feathers hide lesions and retain moisture; draught breeds with chronic progressive lymphoedema can develop persistent folds and secondary infections.
White limbs may be overrepresented in photosensitisation and some contact reactions, but pigment alone does not establish cause. Aggressive daily scrubbing and pulling dry scabs can deepen trauma, delay barrier repair and make the horse resistant to handling. Conversely, coating an infected wet leg with occlusive grease can trap organisms.
Most acute uncomplicated cases resolve once the cause and moisture are controlled. Recurrent or proliferative disease requires targeted sampling because antibiotics alone will not cure mites, fungal infection, vasculitis or liver-associated photosensitisation. Prognosis is guarded for complete resolution when chronic lymphatic thickening and deep skin folds are established, although discomfort and infection can usually be reduced.
Pastern dermatitis is a reaction pattern rather than one disease. Moisture and abrasion permit bacterial overgrowth in some horses, while mites, contact allergy, photosensitisation, vasculitis and chronic progressive lymphoedema require different treatment. Thick feathers can conceal painful fissures and swelling, and forcibly removing adherent crusts can deepen inflammation.
Chronic cases can develop fibrosis that permanently thickens the lower limb.
Screening & Early Detection
The veterinarian examines lesion distribution, limb pigment, feathers, oedema, pain and evidence of cellulitis. The history covers mud, bedding, topical products, sunlight, pasture plants, mites in herd mates and previous antimicrobial or steroid treatment. Temperature and lymph-node enlargement help identify systemic spread.
Crust impression smears and cytology identify bacteria and inflammatory cells. Deep skin scrapings or hair samples investigate mites and dermatophytes; bacterial or fungal culture is chosen after surface debris is removed. Biopsy is valuable for recurrent, nodular, ulcerative or treatment-resistant disease and for suspected vasculitis or immune-mediated inflammation. Blood tests and liver evaluation are indicated when photosensitisation is possible.
Ultrasound may assess abscessation or deeper swelling. Owners should seek urgent care for rapidly expanding hot oedema, fever, severe lameness or discharge tracking above the pastern. A negative mite scraping does not completely exclude infestation. Repeated empirical creams can alter samples, so diagnostic collection is best performed before another treatment cycle when the horse is stable.
Biopsy is considered before immunosuppressive treatment when vasculitis or neoplasia remains possible.
Treatment & Management
The limb is moved to clean dry footing and wetting cycles are reduced. Feathers may be clipped carefully to expose lesions, although clipping inflamed skin can cause further trauma. Crusts are softened with an appropriate antiseptic wash and removed gently only when loose; the skin is rinsed and dried thoroughly. Treatment frequency allows barrier recovery rather than repeated abrasive scrubbing.
Cytology and cause direct medication. Topical or systemic antimicrobials treat documented bacterial infection, acaricides treat mites, and antifungals treat dermatophytosis. Anti-inflammatory medication can be important for immune-mediated or allergic disease but is used cautiously when infection is uncontrolled. Cellulitis, lymphangitis or deep infection requires systemic treatment and monitoring.
Contact irritants are stopped, photosensitive horses are removed from sunlight and the primary liver or plant cause investigated. Chronic progressive lymphoedema needs lifelong feather and fold hygiene, controlled exercise, compression or manual lymphatic care where appropriate, and prompt secondary-infection treatment. Barrier ointment is applied only to clean dry skin and is not a substitute for diagnosis. Recurrence prevention follows the identified mechanism rather than a universal mud product.
Feathers are clipped only when this can be done without traumatising acutely inflamed skin.
Breeds or species affected
Akhal-Teke
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Anglo-Arabian
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Arabian
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Barb
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Caspian
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Kathiawari
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Marwari
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Shagya Arabian
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Thoroughbred
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American Quarter Horse
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American Paint Horse
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Appaloosa
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Australian Stock Horse
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Brumby
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Waler
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Morgan
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Standardbred
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American Saddlebred
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Tennessee Walking Horse
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Missouri Fox Trotter
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Rocky Mountain Horse
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Peruvian Paso
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Criollo
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Mustang
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Canadian Horse
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Andalusian
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Lusitano
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Lipizzaner
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Friesian
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Dutch Warmblood
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Hanoverian
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Holsteiner
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Oldenburg
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Westphalian
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Trakehner
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Selle Français
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Belgian Warmblood
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Danish Warmblood
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Swedish Warmblood
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Swiss Warmblood
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Australian Warmblood
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Irish Sport Horse
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Cleveland Bay
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Württemberger
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Zangersheide
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Knabstrupper
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Orlov Trotter
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Camargue
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Icelandic Horse
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Pony of the Americas
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Quarter Pony
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Miniature Horse
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Clydesdale
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Shire
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Percheron
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Belgian Draft
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Suffolk Punch
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American Cream Draft
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Ardennes
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Breton
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Boulonnais
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Comtois
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Dutch Draft
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North Swedish Horse
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Norwegian Fjord
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Haflinger
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Gypsy Cob
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Irish Draught
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Welsh Pony and Cob
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Connemara Pony
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New Forest Pony
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Dartmoor Pony
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Exmoor Pony
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Shetland Pony
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Highland Pony
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Fell Pony
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Dales Pony
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Australian Pony
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Finnhorse
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Black Forest Horse
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