Pemphigus foliaceus in Horses (Equis) | Vetlexicon
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Pemphigus foliaceus

ISSN 2398-2977


Introduction

  • The most common auto-immune skin disease of the horse.
  • Cause: abnormal immune response.
  • Signs: focal to widespread vesicles, pustules, scales, crusts and alopecia. Lethargy, fever, poor appetite, weight loss, edema, pain pruritis may be associated.
  • Diagnosis: skin biopsy, cytology.
  • Treatment: immunosuppressive agents.
  • Prognosis: guarded to good. May need lifelong treatment.

Presenting signs

  • Presence of crusts, scales, oozing, annular erosions, epidermal collarettes, alopecia.
  • Head and lower extremities are affected.
  • Lethargy, inappetance, weight loss Weight loss: overview, fever.
  • Edema of the ventrum and/or extremities.
  • Variable pruritus and/or pain.

Age predisposition

  • No age predisposition, the disease affects both adults and horses younger than 1 year of age.

Breed/species predisposition

Cost considerations

  • Long-term treatment may be necessary.

Pathogenesis

Etiology

  • Abnormal immune response.

Predisposing factors

General

  • Hereditary predisposition.

Specific

  • Certain drugs, vaccines or stressful situations, eg pregnancy, may trigger the disease.

Pathophysiology

  • Abnormal immune response resulting in auto-antibodies directed against surface proteins on the keratinocyte, which provide intercellular adherence → loss of intercellular cohesion → acantholysis and blister formation.
  • The disease usually occurs spontaneously, but may be triggered by drugs, vaccines, infections or stressful situations.

Type II hypersensitivity

  • Believed to be the immune reaction occurring in this disease.
  • Characterized by the binding of antibodies (with or without complement) to antigens on body tissues resulting in cytotoxicity or cytolysis.
  • In pemphigus foliaceus the auto-antibodies are directed against desmosomal antigens.
  • Pustules or vesicles are the primary lesions and are transient; they are easily ruptured, forming a crust.
  • The disease may be exacerbated by exposure to ultraviolet light.

Timecourse

  • Chronic in most cases, may take weeks to months to be controlled. It can wax and wane.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Knottenbelt D C (2016) Integumentary disorders including cutaneous neoplasia in older horses. Vet Clin Equine 32 (2), 263-281 PubMed.
  • White S D (2015) A diagnostic approach to the pruritic horse. Equine Vet Educ 27 (3), 156-166 Wiley Online Library.
  • Rosenkrantz W (2013) Immune-mediated dermatoses. Vet Clin Equine 29 (3), 607-613 PubMed.
  • Olivry T & Linder K E (2009) Dermatoses affecting desmosomes in animals: a mechanistic review of acantholytic blistering skin diseases. Vet Dermatol 20 (5-6), 313-326 PubMed.
  • Olivry T (2006) A review of autoimmune skin diseases in domestic animals: I – Superficial pemphigus. Vet Dermatol 17 (5), 291-305 PubMed.
  • Zabel S et al (2005) Review of 15 cases of pemphigus foliaceus in horses and a survey of the literature. Vet Rec 157 (17), 505-509 PubMed.
  • Vandenabeele S I J, White S D, Affolter V K et al (2004) Pemphigus foliaceus in the horse: a retrospective study of 20 cases. Vet Dermatol 15 (6), 381-388 PubMed.
  • Lloyd D et al (2000) Stannards illustrated equine dermatology notes: Immunologic diseases. Vet Dermatol 11 (3), 163-178 Wiley Online Library.
  • Johnson P J (1997) Pemphigus foliaceus in a horse. Vet Allergy Clin Immunol (4), 131-134 VetMedResource.
  • Fadok V A (1995) An overview of equine dermatoses characterized by scaling and crusting. Vet Clin North Am Eq Pract Derm 11 (1), 43-51 PubMed.
  • Scott D W (1994) Marked acantholysis associated with dermatophytosis due to Trichophyton equinum in two horses. Vet Derm (3), 105-110 VetMedResource.

Other sources of information

  • Scott D W & Miller W H (2011) Equine Dermatology. 2nd edn. Saunders, USA.
  • Knottenbelt D C (2009) Pascoe’s Principles and Practice of Equine Dermatology. 2nd edn. Saunders, USA.
  • Scott D W (1988) Large Animal Dermatology. W B Saunders. USA.