Horse Side Vet Guide ®

Equine Health Resource

Pastern Dermatitis, Scratches, Mud Fever

Synonyms: Greasy Heel, Mud Foot, Dew Poisoning, Eczematoid Dermatitis, Verrucous Pastern Dermatitis, Foot Rot

Scratches refers to skin crusting and scabbing that affects the lower limbs, below the fetlock. It remains a poorly understood syndrome that can result from allergic, bacterial, fungal, immune-mediated, parasitic, photo-activated, or viral causes, alone or in combination.

It more commonly occurs on the hind limbs, but can affect the front limbs too. In most cases, it affects more than one limb. It is also more common on lower limbs with unpigmented skin with white hair. In a particular horse, it will often only appear on limbs with pink skin. In draft breeds, Chorioptes mites are often part of the problem and require treatment.

Scratches is more common in wet climates and is made worse by wet/dry weather cycles. It is especially common in horses consistently grazing wet pastures and in wet grass.

In some cases, breaks in the skin caused by this condition allows bacteria to enter, causing a very severe infection of the lower limb that appears as sudden onset lameness and limb swelling (Sporadic Lymphangitis). In most cases, a specific diagnosis of the cause for the lesions is not made. Often bacterial infection is a complicating layer on top of the primary cause.

Treatment involves identifying and addressing underlying causes, if possible, and the lesions are often treated with antiseptic shampoos and antibiotic/antifungal/steroid creams.

Prognosis & Relevant Factors

The prognosis in most cases is fair to good, but depends on the underlying causes in a particular horse. Some horses are very susceptible to it. It also depends on the owner's ability to manage the horse in a way that minimizes the risk factors.

As this condition becomes established and the affected tissue become larger, deeper and more widespread, it becomes increasingly difficult to resolve if left untreated.


  • What are the chances that this will reoccur?
  • What management changes must I make to reduce the chance of recurrence?
  • How did it happen in the first place?

    House your horse in dry conditions when possible. Avoid grazing pastures of consistently wet grass. If you do, bring the horse in at the end of the day and carefully dry the legs.

    For draft breeds, trimming of long feathers may be helpful.

    Helpful Terms & Topics in HSVGWritten, Reviewed or Shared by Experts in Equine Health

    Helpful Outside ResourcesCredible Equine Health Information on the Internet

    Author: Doug Thal DVM Dipl. ABVP


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