Greasy Heel

Also known as:

Grease Heel Pastern Folliculitis Pastern Dermatitis Mud Fever

Description

Greasy heel is not a single disease but refers to the clinical presentation of a group of inflammatory skin conditions of the distal limb of the horse. Several aetiologies have been suggested including immunodysregulation, contact dermatitis and genetic (breed) predisposition. Predisposing factors include constant wetting, non-pigmented skin and abrasions to the limb. Multiple bacteria are thought to have a role in the disease and include Dermatophilus congolensis, Pseudomonas aeruginosa and Staphylococcus hyicus.

Signalment

Greasy heel has no sex predilection in the adult horse. Although all breeds are affected, draft horses such as Shires and Clydesdales are more prone to developing the condition; this is thought to be due to an underlying immune-mediated vasculitis.

Clinical signs

Skin lesions are seen most commonly in non-pigmented areas at the palmar or plantar aspect of the pastern. Hindlimbs are most commonly affected and lesions are often symmetrical (although they make affect only one limb). The dermatitis is initially characterised by erythema, alopecia, exudation, pruritus and crusting of the lower limb. Lameness may occasionally be a feature of the condition. In chronic cases, thickening of the skin occurs with hyperkeratosis and fissure formation.

Diagnosis

A detailed history is important in order to aid in determining the underlying cause of the condition. A detailed description of the environment (bedding, quality of turnout, exposure to wet conditions) is particularly important. In order to rule out zoonotic infections such as Dermatophytosis or Cheyletiella, the owner should be questioned to determine if other in-contact animals or humans have been affected.

The seasonal nature of the condition combined with a history of continual wetting may aid in diagnosis. However, the list of differential diagnoses for this condition is lengthy and several important conditions should be ruled out. If lesions are restricted to non-pigmented skin only, liver enzymes and bile acids should be evaluated in order to rule out photosensitisation as a cause of disease. Skin scrapes should be performed in order to rule out parasites such as Chorioptes mites (especially in heavily-feathered horses). Bacterial swabs for culture and skin biopsy may be useful in refractory cases.

In chronic cases, diagnosis may be difficult and a diagnosis of idiopathic pastern dermatitis is often made.

Treatment

Treatment is dependent on the underlying cause but includes removal of environmental triggers and alterations in husbandry. The horse should be removed from wet, muddy conditions and stabled on clean, dry bedding. The affected area should be gently clipped and cleansed with a mild antiseptic solution (e.g. Hibiscrub). Horses that are severely painful may require sedation for this to be performed. The necrotic and exudative skin should be gently debrided away and the area should then be dried thoroughly. Once debridement is complete, topical antibiotic creams may be applied in order to aid healing. Stabling during wet weather should be recommended as well as avoiding turnout before the morning due has dried.

In chronic cases, treatment may be difficult or impossible and may require surgical excision of affected tissue.

Prevention

Prevention is based on minimising exposure to wetting and rigorous attention to cleaning and drying following exercise. Light barrier creams such as petroleum jelly may be useful in protecting the legs during turnout and exercise.

References

• Lloyd, D. H., Littlewood, J. D., Craig, J. M., Thomsett, L. R. (2003) Practical Equine Dermatology Blackwell Publishing
• Pascoe, R. R. (1990) A Colour Atlas of Equine Dermatology Wolfe Publishing Ltd
• Pilsworth, R., Knottenbelt, D (2006) Common Equine Skin Diseases Equine Veterinary Journal Ltd
• Scott, D. W., Miller, W. H. (2003) Equine Dermatology Saunders