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26 Cards in this Set
- Front
- Back
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What is pruritus?
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An unpleasant sensation stimulating the desire to itch
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What is skin function modulated by?
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Neuromediators and peripheral nerves at the periphery
Spinal cord, CNS Immune-endocrine system Autonomic nerves - (Ach) Sensory nerves - neuropeptides, prostanoids and NO |
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What sensory fibers transmit noxious and cold stimuli?
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Thin myelinated A delta fibers
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What fibers transmit pain, heat and itch?
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Non-mylenated C fibers
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What are the factors that can lead to pruritus?
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Make originate in skin or CNS
Can be chronic May be sensory, emotional, cognitive |
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What causes itch due to skin disease, what fibers do they fire?
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Transmitted by C nerve fibers from non specific receptor units in the epidermis and the D-J junction
Ex scabies |
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What causes itch due to systemic disease?
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Imbalances in mu and kappa opioid disease or changes in interleukins or neuropeptides
Ex liver or renal disease |
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What is neuropathic itch?
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Disease in the afferent system
Ex herpes neuropathy |
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What is Psychogenic itch?
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Delusions, OCD, depression
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What are triggers aggravating pruritus?
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Itching - precede the development or consequence
Epidermal barrier - easier penetration of allergens Stress - activation of psycho-neuroendocrine system |
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How to we recognize pruritus?
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See biting, licking, chewing, scratching, gnawing, rubbing
Alopecia Erythema Excoriations |
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How do you approach pruritus?
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Look at factors
Look for diseases Be systematic in approach to diagnosis and treatment Eliminate one factor at a time Keep the owner informed |
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What are the most common causes of pruritus?
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Allergy
-flea -atopic dermatitis -cutaneous adverse food reactions Ectoparasites -sarcaptes -demodex -Cheyletiella, Notoedres Infection -pyoderma -yeast -dermatophytes |
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How do you characterize pruritus?
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Body sites involved
Seasonality Intensity Pruritus or skin lesions 1st Helpful treatments Age at onset |
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What causes this pattern of pruritus?
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Flea allergy
seen in hind end |
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What is the likely cause of this pruritus?
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scabies
on ears, elbows and hock |
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What are examples of seasonal allergies?
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Flea
Atopic dermatitis Insect bite Hypersensitivity |
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What are nonseasonal examples of allergies?
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Scabies, notoedres, cheyletiella, demodex
Food allergy Atopic dermatis Flea allergy Secondary infections |
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How do you grade pruritus?
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Scale of 1-10
Reference point to monitor changes |
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What causes the most pruritus?
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flea allergy
scabies food allergy |
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What is the likely disease if you see pruritus before lesions?
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Allergies
Scabies |
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What is the likely disease if you seen lesions before pruritus?
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Demodicosis
dermatophytosis pyoderma due to secondary endocrine |
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When would you use a diagnosic deep skin scraping
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Demodicosis
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When would you use a dianostic deep skin scraping?
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Scabies cheyletiella, notoedres
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When would you use diagnostic surface cytology?
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Bacteria and yeast
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How do you treat pyoderma? Yeast? Flea? Scabies?
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Pyoderma: topical and systemic antibiotics
Yeast infection: topical and systemic antifungals Fleas: aggressive flea control Scabies: specific parasiticides |
