Authored by: Carissa Wickens, UF/IFAS Equine Extension Specialist

Equine pastern dermatitis (EPD), also commonly referred to as scratches, mud fever, mud rash, greasy heel, or dew poisoning, is an inflammatory skin condition that affects the lower limbs of horses. EPD is often caused by a combination of factors, such as prolonged exposure to wet conditions, which weaken the skin’s barrier allowing pathogens (bacteria or fungi) to penetrate. The condition is characterized by irritation that can lead to infection of the skin typically around the hind pastern or fetlock and sometimes extends to the heel bulbs (figure 1). Recent rainfall and morning dew on pastures can create a wet environment that predisposes and perpetuates causative factors leading to irritation and scabbing seen with EPD. Abrasive grasses and sun exposure have also been implicated in the onset of EPD, though the full range of contributing factors is still not entirely understood.

–

Symptoms and Diagnosis

EPD can affect any breed of horse, but it is most prevalent in horses with long pastern hair (“feathers” on the lower limbs which can retain moisture) and nonpigmented skin (white leg markings). Initially, owners may notice redness, scaling and edema (swelling) in the affected areas which can rapidly progress to oozing, hair matting, hair loss, crusting, and thickening of the skin. If left untreated, lesions can spread to the front of the pastern and fetlock with secondary bacterial infections as a common complication. Lesions on the skin are often itchy and painful, and in more severe cases can affect deeper layers of the skin and the underlying soft tissues leading to cellulitis.

Consult with your veterinarian if you suspect your horse has scratches. Your veterinarian can examine your horse’s lower limbs and conduct testing to help determine the underlying cause of the skin irritation to facilitate the most appropriate and effective treatment.

–

Treatments and Management

Treatment of EPD typically focuses on keeping the affected area(s) clean and dry in combination with the application of topical medications which include antibacterial or antifungal properties to fight infection and corticosteroids or anti-inflammatory drugs to reduce swelling and discomfort. In more severe cases, treatment may include systemic treatments such as oral antibiotics. Topical antibacterial products include chlorhexidine and miconazole shampoos and ointments as well as other topical treatments which include specific ingredients such as zinc oxide and manuka honey. Avoid picking at crusts, instead soften crusts by washing the horse’s legs. Most horses with scratches respond well to treatment, especially when the condition is identified and treated early.

Suggested management practices for reducing the occurrence and severity of EPD:

• Maintain good grooming practices to promote overall skin health and to facilitate early detection of skin irritations
• Keep horses prone to scratches in a clean, dry stall during wet weather to limit exposure to wet conditions (with increased time in the stall, be sure to provide ample forage and some form of enrichment)
• Ensure proper drainage around your farm/property or move horses to a drier area (alternate pasture or paddock) during heavy rain events to prevent exposure to standing water
• Wait until the morning dew has dried before turning horses out on pasture (again, the goal is to reduce exposure to wet conditions)
• Susceptible horses may benefit from application of a barrier cream before turnout/exposure to moisture or other environmental irritants (consult with your veterinarian for specific recommendations)

–

References and Further Reading:

How to Treat Scratches in Horses in Humid Environments – The Horse

Scratches in Horses: Causes, Symptoms & Treatments | Mad Barn

Getting a Handle on Scratches in Horses – The Horse

Understanding and Treating Scratches in Horses | Purdue University Equine Hospital

0