Contact Dermatitis

• Results due to exposure to chemicals (not immunologic reaction)
  • Acids, alkali, detergents, irritant plants etc.
• In cats and dogs lesions usually on skin of abdomen, feet, chest, eyelids, axillae
• In horses lesions on muzzle, lower limbs, under tack
• Grossly:
  • Erythematous pathes and papules
  • Occasionally vesicles
  • Lesions caused by self-trauma include ulcers and crusts
• Microscopically:
  • Hyperplastic, spongiotic dermatitis
  • Superficial perivascular inflammation
  • Necrosis may be caused by corrosive substances