Equis ISSN 2398-2977

Skin: pastern dermatitis - overview

Synonym(s): Greasy heel, Scratches, Cracked heels, Grapes, Verrucous pododermatitis, Verrucose pododermatitis, Mud fever, Mud rash, Dew poisoning

Contributor(s): Beatrice Funiciello, Jeanette Bannoehr

Introduction

  • Description: pastern dermatitis is a common cutaneous reaction pattern of the horse.
  • Cause: the syndrome of pastern dermatitis comprises primary and secondary causes, including viral, bacterial and fungal infections, parasitic infestations, allergic/immune-mediated conditions, traumatic disorders, contact reactions (hypersensitivity or chemicals) and actinic dermatitis. Predisposing factors, eg genetic and/or environmental, are important.
  • Signs: clinical signs most commonly affect the caudal pastern regions but may involve the fetlock and cannon regions in some cases. Signs may overlap despite different etiologies and include erythema, papules, alopecia, scaling, crusting, ulcerations, edema, lichenification. Pain and pruritus are variable. A chronic form in draft breeds is associated with hyperkeratosis, nodular and fibrous proliferation with papillomatous areas, fissures and chronic exudation.
  • Diagnosis: systematic and detailed history taking and thorough examination of the patient and environment. Hair brushings, hair plucking (trichography), cytology, bacterial and fungal culture, skin biopsy with histopathological examination. Blood analysis may be required in some cases.
  • Treatment: must address primary and secondary/perpetuating factors.
  • Prognosis: from good to poor depending on etiology, chronicity and response to the therapy.

Pathogenesis

Etiology

Predisposing factors

  • Environmental conditions: chronic wetting of the distal limbs and/or contact with soil or bedding are common cause of skin irritation. 
  • A genetic predisposition is reported in the above-mentioned breeds and suspected in individual horses with recurrent episodes.
  • Pastern dermatitis is more common in horses with heavily feathered pasterns.
  • Pastern dermatitis commonly affects non-pigmented skin and hair; lesions may be restricted to those areas.

Pathophysiology

  • Often multifactorial.
  • A primary factor causes initial skin irritation and predisposes to secondary conditions that worsen clinical signs. 
  • Intense (often non-veterinary prescribed) topical treatment can exacerbate inflammation and complicate the situation.
  • In chronic cases, it may not be possible to identify the primary cause due to the chronicity and presence of secondary/perpetuating factors.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Aufox E E, Frank L A, May E R, Kania S A (2018) The prevalence of Dermatophilus congolensis in horses with pastern dermatitis using PCR to diagnose infection in a population of horses in southern USA. Vet Dermatol 29 (5), 435-e144 PubMed.
  • Sloet van Oldruitenborgh-Oosterbaan M M & Grinwis G C M (2016) Viral skin diseases in the Netherlands. Equine Vet Educ, WileyOnline
  • Yu A A (2013) Equine Pastern Dermatitis. Vet Clin North Am Equine Pract 29 (3), 577-588 PubMed.
  • Psalla D, Ruefenacht S, Stoffel M H et al (2013) Equine pastern vasculitis: A clinical and histopathological study. Vet J 198 (2), 524-530 PubMed.
  • Colles C M, Colles K M & Galpin J R (2010) Equine pastern dermatitis. Equine Vet Educ 22 (11), 566-570 VetMedResource.
  • Pilsworth R C & Knottenbelt D C (2007) Papillomatosis (viral warts). Equine Vet Educ 19 (8), 444-446 VetMedResource.
  • Pilsworth R C & Knottenbelt D C (2006) Pastern and heel dermatitis. Equine Vet Educ 18 (2), 93-95 VetMedResource.
  • Risberg A I, Webb C B, Cooley A J et al (2005) Leucocytoclastic vasculitis associated with Staphylococcus intermedius in the pastern of a horse. Vet Rec 156 (23), 740-743 PubMed.
  • De Cock H E V, Affolter V K, Wisner E R et al (2003) Progressive Swelling, Hyperkeratosis, and Fibrosis of Distal Limbs in Clydesdales, Shires, and Belgian Draft Horses, Suggestive of Primary Lymphedema. Lymphat Res Biol 1 (3), 191-199 PubMed.
  • Knottenbel D C (2002) Vasculitis: just what does it mean? Equine Vet Educ 14 (5), 247-251 VetMedResource.
  • Ferraro G L (2001) Pastern dermatitis in Shires and Clydesdales. J Equine Vet Sci 21 (11), 524-526 VetMedResource.

Other sources of information

  • Scott D W & Miller W H (2011) Equine Dermatology. 2nd ed. St. Saunders, USA. 
  • Knottenbelt, D C (2009) Pascoe’s Principles and Practice of Equine Dermatology. 2nd ed. Saunders, USA.


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