Bovis ISSN 2398-2993

Contact dermatitis

Contributor(s): Catherine Fraser , Ben Dustan

Introduction

  • Cause: may be irritant contact dermatitis (more common) or allergic contact dermatitis (rare).
  • Signs: variable pruritus and pain, erythema, macules, papules, pustules, edema, vesicles, crusts in contact areas with reduced hair cover.
  • Diagnosis: removal of contact irritant leads to resolution.
  • Treatment: eliminate irritant from environment.
  • Prognosis: good.

Pathogenesis

Etiology

  • Cement dust, freshly laid cement, plaster dust, acids and alkalis, corrosive substances eg waste motor oil.
  • Weed and insecticidal sprays, fertilizers eg nitrolime (calcium cyanamide).
  • Cleaning products (soaps, shampoos, detergents, disinfectants).
  • Some plants eg Commelinanceae family including Tradescantiae, also Urtica spp, Helenium, Euphorbia, Cleome, Digitalis (foxglove) , Pteridium (bracken)  Bracken fern poisoning.
  • Urine, feces and wound secretions.
  • Preservatives, dyes and polishes eg on head collars, calf jackets, harnesses for draught animals.
  • Plastics and rubber eg calves fed milk replacer from buckets.
  • Wood preservatives eg creosote.
  • Bedding, such as treated wood products, paper waste, 'green' bedding (treated manure), sand etc.

Predisposing factors

General

  • Increased moisture decreases the normal barrier function of the skin allowing closer contact of the irritant or allergenic substance to the skin surface.
  • Prolonged immersion in water, urine and fecal contamination of skin and excessive sweating all predispose.
  • Sparsely haired body areas predisposed eg muzzle, face, lower limbs, perineum and ventrum.

Pathophysiology

  • Irritant contact dermatitis caused by prolonged skin contact with irritant substances in sufficient concentration to cause dermatitis in all individuals without immunological mediation.
  • Allergic contact dermatitis caused by type IV hypersensitivity reaction where antigens penetrate the skin in suscepible individuals. Requires prior contact and sensitization to the material eliciting the dermatitis.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed Papers

Other sources of information

  • Scott D W (1988) Large Animal Dermatology. W B Saunders. Philadelphia.
  • Smith B P. Large Animal Internal Medicine. 5th edn. Elsevier.


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