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E. Simko WCVM

Repaire and regeneration. Prerequisites for healing: Debridement Tissue scaffold Germinal cells Blood supply. Healing: First intention Second intention. Reference reading: Repair of the skin pp318-322, in Applied Veterinary Histology, W. J. Banks, 1993. E. Simko WCVM.

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E. Simko WCVM

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  1. Repaire and regeneration • Prerequisites • for healing: • Debridement • Tissue scaffold • Germinal cells • Blood supply • Healing: • First intention • Second intention Reference reading: Repair of the skin pp318-322, in Applied Veterinary Histology, W. J. Banks, 1993 E. Simko WCVM

  2. Physical and chemical injuries • 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. Immunologic diseases • Allergy (Hypersensitivity) • severe reaction to harmless foreign antigen • Autoimmune dz • immune reaction against self-antigens Pathogenesis: tissue damage is mediated by four immune reactions: Type I, II, III, and IV E. Simko WCVM

  4. Immunologic diseases IgE Mast cell Allergen Type I E. Simko WCVM

  5. Immunologic diseases Type II IgG T cell Complement Cytotoxic effect E. Simko WCVM

  6. Immunologic diseases Type III Immune complex deposition Complement E. Simko WCVM

  7. Immunologic diseases Type IV Antigens Sensitized T cell Chemotaxis and activation of macrophages Cytokines E. Simko WCVM

  8. Immunologic diseases Allergic dermatitides • 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. Immunologic diseases - Allergic dz Atopy • 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. Immunologic diseases - Allergic dz Diagnosis • There is no single confirmatory test • Skin biopsy • Rule out other allergies • Intradermal allergy testing • ELISA for allergen specific IgE E. Simko WCVM

  11. Immunologic diseases - Allergic dz Flea-bite allergic dermatitis • 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. Immunologic diseases - Allergic dz Diagnosis • Skin biopsy • Demonstration of fleas • Provocative exposure and response to therapy E. Simko WCVM

  13. Immunologic diseases - Allergic dz Food hypersensitivity dermatitis • Type I and/or type IV reactions • Non-seasonal erythema, urticaria, alopecia, pruritus • with self-inflicted trauma (licking, rubbing) E. Simko WCVM

  14. Immunologic diseases - Allergic dz Diagnosis • Skin biopsy • Rule out other allergies • Elimination diet trial (with absolute compliance) E. Simko WCVM

  15. Immunologic diseases - Allergic dz Allergic contact dermatitis • 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. Immunologic diseases Autoimmune dermatoses • 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. Immunologic diseases - Autoimmune dz Pemphigus & Pemphigoid • Group of vesicular/pustular diseases • Pemphigus foliaceus (Ca, Fe, Eq, Cap) • Acantholysis (anti-desmosomal antibodies) • Bullous pemphigoid (Ca, Eq) • (anti-hemidesmosomal antibodies) C C E. Simko WCVM

  18. Immunologic diseases - Autoimmune dz C Lupus • Type III reaction • Systemic lupus erythematosus • Multiorgan disease • Discoid lupus erythematosus • Skin of the face • Ab-Ag deposition E. Simko WCVM

  19. Immunologic diseases - Autoimmune dz C Familial canine dermatomyositis • Autosomal dominant disease • Puppies and young dogs • Type III reaction - vasculitis E. Simko WCVM

  20. Immunologic diseases - Autoimmune dz Diagnosis of autoimmune diseases • Clinical signs • Histology • Immunohistochemistry E. Simko WCVM

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