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− | ==Chemical damage==
| + | #REDIRECT[[:Category:Integumentary System - Environmental Pathology]] |
− | ===[[Contact Dermatitis]]===
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− | ===[[Ergot Poisoning]]===
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− | ===[[Fescue Poisoning]]===
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− | ===[[Selenium Poisoning]]===
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− | ==Physical damage==
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− | ===[[Acral Lick Dermatitis]]===
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− | ===[[Callus]]===
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− | ===[[Feline Psychogenic Alopecia]]===
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− | ===[[Injection Site Reaction]]===
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− | ===[[Intertrigo]]===
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− | ===Pyotraumatic dermatitis===
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− | *Also called '''acute moist dermatitis''' or ''''hot spot''''
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− | *Common in dogs, especially self-inflicted due to pain and itching
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− | *Usual causes: [[Skin Immunologic - Pathology|allergies]], irritants, matted hair, [[Parasitic skin infections - Pathology|parasites]]
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− | *Lesions tend to be worse in hot and humid weather
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− | *Grossly:
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− | **Hairless, red and moist lesion
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− | **Fluid exudate
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− | **Edges are circumscribed and red
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− | *Microscopically:
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− | **Superficial erosive to ulcerative exudative dermatitis
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− | **May be deeper suppurative folliculitis
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− | [[Category:Integumentary System - Physical Damage]]
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− | ===Radiation damage===
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− | *Cells sensitive to radiation include [[Skin Glossary - Pathology|anagen]] hair follicles, germinal basal cells, melanocytes and endothelial cells
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− | *Early changes:
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− | **Erythema, epidermal blisters and oedema, erosions and ulceration
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− | **Healed by scarring, hyperpigmentation with lower doses and hypopigmentation with higher doses
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− | **Temporary or permanent alopecia
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− | *Chronic changes:
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− | **Scarring, altered pigmentation, alopecia
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− | **Epidermal and adnexal atrophy
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− | **Degeneration of vascular and elastic tissue
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− | **Fibrosis of dermal and subcutaneous tissue
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− | **Ulceration
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− | **In severe damage, squamous cell carcinoma may develop
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− | [[Category:Integumentary System - Physical Damage]]
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− | ===Low temperature damage===
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− | *Prolonged cold can cause ice crystal formation and vascular injury resultic in damage to tissue due to increased intracellular salt concentration
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− | *Slow chilling can cause vasoconstriction, cellular damage -> secondary vasodilation and increased permeability -> oedema
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− | *Severe and persistent cold causes vasoconstriction, increase in blood viscosity and tissue anoxia
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− | *Lesions may occur in wet or hypoglycaemic neonates or animals recently moved from warm to cold environment
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− | *Areas affected are extremities
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− | *Lesions consist of [[Necrosis - Pathology#Gangrene|gangrene]] and necrotic tissue
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− | [[Category:Integumentary System - Physical Damage]] | |
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− | ===High temperature damage===
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− | *May result from excessive heat, liquids, flames, friction, lightning, electricity
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− | *Partial or full thickness burns (first, second and third degree burns)
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− | *Full thickness burns:
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− | **Total destruction of skin and adnexa
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− | **Has to be repaired by grafting
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− | **Life threatening
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− | *Partial thickness burns:
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− | **Some structures preserved -> regeneration may occur
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− | **Grossly:
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− | ***Erythema (capillary dilation)
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− | ***Oedema (increased permeability of capillaries)
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− | ***Vesicles
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− | **Microscopically:
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− | ***[[Necrosis - Pathology#Coagulation Necrosis|Coagulation necrosis]] of epidermis
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− | ***Subepidermal vesiculation
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− | ***Necrosis of adnexa
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− | ***Degenerated subepidermal collagen
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− | ***May involve large numbers of [[Neutrophils|neutrophils]] if secondary ifection is present
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− | [[Category:Integumentary System - Physical Damage]]
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− | ==Sunlight damage==
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− | *Transient erythema may develop into sunburn erythema (warmth, swelling, pain)
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− | *Diffusion of inflammatory mediators (''e.g.'' cytokines) from damaged keratinocytes and endothelial cells
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− | *Photooxidation of existing melanin -> pigment darkening
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− | *Melanogenesis
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− | *Immune responses of skin are reduced by UV light
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− | [[Category:Integumentary System - Sunlight Damage]]
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− | ===Solar dermatosis and neoplasia===
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− | *Caused by chronic sunlight damage
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− | *Damaged tissue generates free radicals than may damage nucleis acids and proteins
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− | *If damage repaired prior to mitosis - no lasting effect
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− | *If mitosis occurs before repair, post-mitotic repair is prone to faults and DNA mutations may result in neoplasia
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− | [[Category:Integumentary System - Sunlight Damage]]
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− | ===Solar dermatitis===
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− | *Particularly in white animals and where little or no hair is present
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− | *Grossly:
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− | **[[Skin Glossary - Pathology|Erythema, scaling and crusting]]
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− | **-> Wrinkled nand thickened skin
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− | ** Squamous cell carcinoma or haemangiosarcoma/haemangioma may develop
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− | *Microscopically:
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− | **Dyskeratotic cells
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− | **Intercellular oedema
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− | **Vacuolated keratinocytes
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− | **Followed by [[Skin Glossary - Pathology|hyperkeratosis, parakeratosis and acanthosis]]
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− | **Endothelial swelling
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− | **Haemorrhage
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− | **Hyperplasia
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− | **Dermal fibrosis
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− | **Dogs may develop actinic [[Skin Glossary - Pathology|comedones]]
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− | [[Category:Integumentary System - Sunlight Damage]]
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− | ===[[Photosensitisation]]===
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− | ===Photoenhanced dermatoses===
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− | *Many [[Skin Immunologic - Pathology|immune-mediated]] cutaneous disease are made worse by sunlight
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− | **Lupus erythematosus
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− | **Dermatomyositis
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− | **Pemphigus erythematosus
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− | *Vasculitis in extremities, especially white-haired horses
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− | *Grossly:
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− | **Erythematous, well circumscribed crusted lesions or hyperkeratotic [[Skin Glossary - Pathology|plaques]]
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− | *Microscopically:
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− | **Vasculitis of superficial dermal vessels
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− | **Thrombi may be seen
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− | [[Category:Integumentary System - Sunlight Damage]]
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