Understanding Pastern Dermatitis (Greasy Heel) and Its Pathophysiology
Pastern Dermatitis, frequently referred to by owners as 'scratches,' 'mud fever,' or 'greasy heel,' is not a single disease but a syndrome characterized by inflammation of the skin on the lower limb. This condition can resemble Atopic Dermatitis in its inflammatory nature, although the triggers are predominantly environmental and microbial rather than purely allergic. The condition typically manifests as an exudative crusting of the skin that can quickly lead to painful fissures.
Classifying the Degrees of Dermatitis
Clinicians often categorize the severity of the lesion. Mild cases present with simple scaling and minor hair loss, often mistaken for Fly Bite Dermatitis by some owners due to the similar crusting appearance. Severe, chronic cases can evolve into proliferative masses often called 'grapes,' which are difficult to treat due to the formation of scar tissue that traps bacteria.
Identifying Symptoms and Diagnostic Signs
Early detection is critical. Owners should look for matted hair, thick yellow or white crusts, and warmth around the pastern area. If the condition is not managed, it may progress to severe edema.
Warning Signs of Secondary Infection
If the skin feels hot, the horse demonstrates significant lameness, or there is an unpleasant, rancid odor, immediate intervention is required. This may indicate a deep bacterial infection that could lead to lymphangitis, a life-threatening inflammatory condition of the lymphatic vessels.
Etiology: Causes and Environmental Risk Factors
While often caused by opportunistic bacteria, the condition is heavily tied to the environment. Horses with long 'feathering' (hair on the lower legs) are more prone to trapped moisture, similar to how Hot Spots (Acute Moist Dermatitis) persist in thick-coated dogs. Other factors include contact dermatitis from irritants in stall bedding or abrasive surfaces.
Genetic and Management Predispositions
Draft breeds with heavy leg hair are at a distinct disadvantage. Owners must manage these breeds with extra vigilance, as they are prone to Footpad Hyperkeratosis as a secondary thickening of the skin barrier in other species, but in equines, it presents as massive proliferative skin changes.
Diagnostic Protocols
Veterinarians typically utilize physical examination and skin scrapings to differentiate the infection. If the infection is widespread, a skin biopsy may be necessary to rule out autoimmune conditions or Zinc-Responsive Dermatosis which can sometimes present with similar crusting patterns in the limbs.
Strategic Treatment and Therapeutic Approaches
Treatment involves the 'clip, clean, and keep dry' mantra. Surgical debridement of proliferative 'grapes' may be necessary. Topical silver sulfadiazine or antiseptic chlorhexidine scrubs are the gold standard for controlling the bacterial load.
Long-Term Management and Prevention
Prevention is rooted in environmental hygiene. Stalls must be kept clean, and muddy paddocks should be fenced off. For horses prone to recurrent issues, a specialized grooming routine to keep the pasterns clean and dry is non-negotiable.
