SAD - Chapter 14 - Keratinization Defects Flashcards
Is selenium sulfide keratolytic or keratoplastic? How?
both – alters the epidermal turnover rate and interferes with hydrogen bond formation in keratin
Adverse effects of benzoyl peroxide?
drying, can induce a contact dermatitis (<10% of patients), bleaches clothing, hair, furniture
seborrhea
chronic skin disease of dogs characterized by a defect in keratinization with increased scale formation, excessive greasiness of the skin and haircoat, sometimes by secondary inflammation
How do keratoplastic agents work?
attempt to renormalize the keratinization and abnormal epithelialization that is present in keratinization disorders
T/F: Salicylic acid is antipruritic and bacteriostatic.
TRUE
How does tar normalize epidermal proliferation? Is it keratolytic or keratoplastic?
decreases DNA production, with a resultant decrease in the mitotic index of the epidermal basal cells; keratoplastic
Is benzoyl peroxide keratolytic or keratoplastic? How?
keratolytic; metabolized in the skin to benzoic acid –> lyses intercellular substance in the horny layer
How does sulfur exert its antibacterial, antifungal, and antiparasitic properties?
formation of pentathionic acid and hydrogen sulfide
Laboratory alterations associated with isotretinoin
hypertriglyceridemia, hypercholesterolemia, ALT, AST, ALP
examples of humectants
propylene glycol, glycerin, colloidal oatmeal, urea, sodium lactate, lactic acid
What do follicular flushing agents do?
help remove follicular secretions and bacteria and decrease follicular hyperkeratosis
T/F: Selenium sulfide is a good degreaser.
True – the best degreaser in one study
What is the optimal stratum corneum water concentration to promote softness and pliability?
20-35%
Toxicity of isotretinoin in the cat
conjunctivitis, diarrhea, anorexia, vomiting
xerosis
skin dryness, caused by decreased water content
Why are pure tar products no longer used in veterinary medicine?
toxicity (especially to cats), localized irritation, odiferous, photosensitization, carcinogenic
T/F: Benzoyl peroxide is antibacterial and antipruritic.
True – is also degreasing and follicular flushing
DDX for marked follicular plugging
vitamin A-responsive dermatosis, hypercortisolism, sebaceous adenitis, generalized demodicosis, follicular dysplasia
What effect does vitamin D exert on keratinocytes?
inhibit keratinocyte proliferation, induce terminal differentiation of keratinocytes, decrease immunologic reactivity by reduced proliferation or transcription of various cytokines and reduced antigen-presenting function of Langerhans cells
emollients
agents that soften or soothe the skin
T/F: Sulfur is a good degreaser and good at follicular flushing.
False - poor degreaser and mild follicular flushing agent
histopathologic findings for idiopathic nasodigital hyperkeratosis
irregular to papillated epidermal hyperplasia, marked orthokeratotic to parakeratotic hyperkeratosis
humectants
hygroscopic agents are moisturizers that work by being incorporated into the stratum corneum and attracting water; draw water from the deep epidermis and dermis and from the environment if the relative humidity is greater than 70%
Histopathologic findings for thymoma-associated exfoliative dermatitis. Characteristic of what other diseases?
cell-poor hydropic interface dermatitis with exocytosis of CD3 or CD8+ lymphocytes into the surface and/or follicular epithelium; apoptotic keratinocytes in the basal layer and stratum spinosum; sebaceous gland may be infiltrated or absent; Erythema multiforme + Lupus
What drugs that influence epidermal turnover can cause an exfoliative dermatitis near the onset of treatment or after discontinuation of the drug?
hormones (thyroid), cytotoxic agents (steroids), retinoic acids
examples of emollients
vegetable oils (olive, cottonseed, corn, peanut); animal oils (lard, whale oil, anhydrous lanolin, lanolin with water), silicones, hydrocarbons (paraffin and petrolatum, mineral oil), waxes (white wax, yellow wax, spermaceti)
Toxicity of isotretinoin in the dog
conjunctivitis, hyperactivity, pruritus, pedal/mucocutaneous junction erythema, stiffness, vomiting, diarrhea, KCS, skeletal abnormalities
Is salicylic acid keratolytic or keratoplastic?
at typical concentrations (0.1-2%) is keratoplastic; at stronger concentrations (3-6%) is keratolytic–solubilizes the intercellular cement, causing shedding and softening of the stratum corneum
How do keratolytic agents work?
facilitate decreased cohesion among corneocytes, desquamation, and shedding –> results in softening of stratum corneum an deasy removal of scale
Histopathologic findings in feline acne
follicular keratosis, plugging, and dilatation (comedo); perifolliculitis, folliculitis, furunculosis with an associated pyogranulomatous dermatitis
DDX for thymoma-associated exfoliative dermatitis
SLE, FeLV or FIV dermatitis, drug reaction, demodicosis, hypercortisolism with a secondary infection (bacteria, dermatophyte, Malassezia)
Why does alopecia occur with tail gland hyperplasia?
friction and glandular pressure on hair follicles
moisturizers
increase the water content of the stratum corneum
What shampoo ingredients are most effective at removing scale from the skin?
selenium sulfide, colloidal oatmeal > sulfur-salicylic acid > benzoyl peroxide, ethyl lactate, chlorhexidine (all ineffective)
Canine ear margin dermatosis is most common in what breed?
Dachshunds
DDX for nasodigital hyperkeratosis
congenitohereditary disorders of keratinization, distemper or leishmaniasis, pemphius foliaceus, drug reaction, DLE, zinc-responsive and generic dog food dermatosis, necrolytic migratory erytheam, cutaneous lymphoma
What is naturally occurring vitamin A metabolized to? What is its role?
retinol and retinoic acid; both are important in the induction and maintenance of normal growth and differentiation of keratinocytes; only retinol has all of the known functions of vitamin A*
Is sulfur keratoplastic or keratolytic? Why?
both keratoplastic or keratolytic; keratolytic - superficial effect on the horny layer and the formation of hydrogen sulfide; keratoplastic - deeper action of the sulfur on the basal layer of the epidermis and by the formation of cysteine
DDX for nasal hyperkeratosis
hereditary nasal hyperkeratosis of the Lab, DLE, pemphigus erythematosus
