Non infectious dermatoses

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Non infectious dermatoses

  1. 1. E. Simko WCVM Healing: • First intention • Second intention Prerequisites for healing: • Debridement • Tissue scaffold • Germinal cells • Blood supply Reference reading: Repair of the skin pp318-322, in Applied Veterinary Histology, W. J. Banks, 1993
  2. 2. • Extreme temperatures (cold and burns) • Solar injury (direct effect and photosensitization) • Chemical/toxic injuries (ergot, fescue, Se) • Self-inflicted injury Acral lick dermatitis (lick granuloma) Feline psychogenic alopecia Pyotraumatic dermatitis (hot spots) • Injection site reactions • Intertrigo (skin fold dermatitis) E. Simko WCVM
  3. 3. • Allergy (Hypersensitivity) severe reaction to harmless foreign antigen E. Simko WCVM • Autoimmune dz immune reaction against self-antigens Pathogenesis: tissue damage is mediated by four immune reactions: Type I, II, III, and IV
  4. 4. Immunologic diseases Allergen IgE Mast cell E. Simko WCVM
  5. 5. Immunologic diseases E. Simko WCVM IgG Cytotoxic effect Complement T cell
  6. 6. Immunologic diseases E. Simko WCVM ComplementImmune complex deposition
  7. 7. Immunologic diseases Sensitized T cell Antigens Cytokines Chemotaxis and activation of macrophages E. Simko WCVM
  8. 8. Immunologic diseases • Allergy (Hypersensitivity) severe reaction to harmless foreign antigen • Mediated by type I and/or type IV reactions • Common in dogs and horses, less common in cats and uncommon in food animals • Erythema, pruritus, self-induced trauma E. Simko WCVM
  9. 9. Immunologic diseases - Allergic dz • Inherited predisposition to type I reaction • Average age of onset is from 1 to 3 years • Respiratory route of allergen exposure (dogs) • Lesions: erythema, urticaria, self-inflicted trauma (licking, rubbing) E. Simko WCVM
  10. 10. Immunologic diseases - Allergic dz • There is no single confirmatory test • Skin biopsy • Rule out other allergies • Intradermal allergy testing • ELISA for allergen specific IgE Diagnosis E. Simko WCVM
  11. 11. Immunologic diseases - Allergic dz • Most common allergic dermatitis in dogs and cats • Type I and type IV reactions to flea saliva • Seasonal pruritus with self-inflicted trauma (excoriation) and alopecia E. Simko WCVM
  12. 12. Immunologic diseases - Allergic dz • Skin biopsy • Demonstration of fleas • Provocative exposure and response to therapy Diagnosis E. Simko WCVM
  13. 13. Immunologic diseases - Allergic dz • Type I and/or type IV reactions • Non-seasonal erythema, urticaria, alopecia, pruritus with self-inflicted trauma (licking, rubbing) E. Simko WCVM
  14. 14. Immunologic diseases - Allergic dz • Skin biopsy • Rule out other allergies • Elimination diet trial (with absolute compliance) Diagnosis E. Simko WCVM
  15. 15. Immunologic diseases - Allergic dz • Type IV reaction to chemicals (dyes, plant, soaps, detergents,…) • Erythema, pruritus with self-inflicted trauma (exudation, crusts, alopecia) • Diagnosis Skin biopsy Elimination trial E. Simko WCVM
  16. 16. Immunologic diseases • Vesiculo-pustular dz often presented as persistent erosions and crusting • Autoimmune dz immune reaction against self-antigens • Mediated by type II or III reactions • Variably pruritic, if not complicate by pyoderma E. Simko WCVM
  17. 17. Immunologic diseases - Autoimmune dz • Group of vesicular/pustular diseases • Pemphigus foliaceus (Ca, Fe, Eq, Cap) Acantholysis (anti-desmosomal antibodies) • Bullous pemphigoid (Ca, Eq) (anti-hemidesmosomal antibodies) E. Simko WCVM
  18. 18. Immunologic diseases - Autoimmune dz • Type III reaction • Systemic lupus erythematosus Multiorgan disease • Discoid lupus erythematosus Skin of the face • Ab-Ag deposition E. Simko WCVM
  19. 19. Immunologic diseases - Autoimmune dz • Autosomal dominant disease • Puppies and young dogs • Type III reaction - vasculitis E. Simko WCVM
  20. 20. Immunologic diseases - Autoimmune dz • Clinical signs • Histology • Immunohistochemistry E. Simko WCVM

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