SAD - Chapter 14 - Keratinization Defects

Question 1

Is selenium sulfide keratolytic or keratoplastic? How?

Answer 1

both – alters the epidermal turnover rate and interferes with hydrogen bond formation in keratin

Question 2

Adverse effects of benzoyl peroxide?

Answer 2

drying, can induce a contact dermatitis (<10% of patients), bleaches clothing, hair, furniture

Question 3

seborrhea

Answer 3

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

Question 4

How do keratoplastic agents work?

Answer 4

attempt to renormalize the keratinization and abnormal epithelialization that is present in keratinization disorders

Question 5

T/F: Salicylic acid is antipruritic and bacteriostatic.

Answer 5

TRUE

Question 6

How does tar normalize epidermal proliferation? Is it keratolytic or keratoplastic?

Answer 6

decreases DNA production, with a resultant decrease in the mitotic index of the epidermal basal cells; keratoplastic

Question 7

Is benzoyl peroxide keratolytic or keratoplastic? How?

Answer 7

keratolytic; metabolized in the skin to benzoic acid –> lyses intercellular substance in the horny layer

Question 8

How does sulfur exert its antibacterial, antifungal, and antiparasitic properties?

Answer 8

formation of pentathionic acid and hydrogen sulfide

Question 9

Laboratory alterations associated with isotretinoin

Answer 9

hypertriglyceridemia, hypercholesterolemia, ALT, AST, ALP

Question 10

examples of humectants

Answer 10

propylene glycol, glycerin, colloidal oatmeal, urea, sodium lactate, lactic acid

Question 11

What do follicular flushing agents do?

Answer 11

help remove follicular secretions and bacteria and decrease follicular hyperkeratosis

Question 12

T/F: Selenium sulfide is a good degreaser.

Answer 12

True – the best degreaser in one study

Question 13

What is the optimal stratum corneum water concentration to promote softness and pliability?

Answer 13

20-35%

Question 14

Toxicity of isotretinoin in the cat

Answer 14

conjunctivitis, diarrhea, anorexia, vomiting

Question 15

xerosis

Answer 15

skin dryness, caused by decreased water content

Question 16

Why are pure tar products no longer used in veterinary medicine?

Answer 16

toxicity (especially to cats), localized irritation, odiferous, photosensitization, carcinogenic

Question 17

T/F: Benzoyl peroxide is antibacterial and antipruritic.

Answer 17

True – is also degreasing and follicular flushing

Question 18

DDX for marked follicular plugging

Answer 18

vitamin A-responsive dermatosis, hypercortisolism, sebaceous adenitis, generalized demodicosis, follicular dysplasia

Question 19

What effect does vitamin D exert on keratinocytes?

Answer 19

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

Question 20

emollients

Answer 20

agents that soften or soothe the skin

Question 21

T/F: Sulfur is a good degreaser and good at follicular flushing.

Answer 21

False - poor degreaser and mild follicular flushing agent

Question 22

histopathologic findings for idiopathic nasodigital hyperkeratosis

Answer 22

irregular to papillated epidermal hyperplasia, marked orthokeratotic to parakeratotic hyperkeratosis

Question 23

humectants

Answer 23

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%

Question 24

Histopathologic findings for thymoma-associated exfoliative dermatitis. Characteristic of what other diseases?

Answer 24

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

Question 25

What drugs that influence epidermal turnover can cause an exfoliative dermatitis near the onset of treatment or after discontinuation of the drug?

Answer 25

hormones (thyroid), cytotoxic agents (steroids), retinoic acids

Question 26

examples of emollients

Answer 26

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)

Question 27

Toxicity of isotretinoin in the dog

Answer 27

conjunctivitis, hyperactivity, pruritus, pedal/mucocutaneous junction erythema, stiffness, vomiting, diarrhea, KCS, skeletal abnormalities

Question 28

Is salicylic acid keratolytic or keratoplastic?

Answer 28

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

Question 29

How do keratolytic agents work?

Answer 29

facilitate decreased cohesion among corneocytes, desquamation, and shedding –> results in softening of stratum corneum an deasy removal of scale

Question 30

Histopathologic findings in feline acne

Answer 30

follicular keratosis, plugging, and dilatation (comedo); perifolliculitis, folliculitis, furunculosis with an associated pyogranulomatous dermatitis

Question 31

DDX for thymoma-associated exfoliative dermatitis

Answer 31

SLE, FeLV or FIV dermatitis, drug reaction, demodicosis, hypercortisolism with a secondary infection (bacteria, dermatophyte, Malassezia)

Question 32

Why does alopecia occur with tail gland hyperplasia?

Answer 32

friction and glandular pressure on hair follicles

Question 33

moisturizers

Answer 33

increase the water content of the stratum corneum

Question 34

What shampoo ingredients are most effective at removing scale from the skin?

Answer 34

selenium sulfide, colloidal oatmeal > sulfur-salicylic acid > benzoyl peroxide, ethyl lactate, chlorhexidine (all ineffective)

Question 35

Canine ear margin dermatosis is most common in what breed?

Answer 35

Dachshunds

Question 36

DDX for nasodigital hyperkeratosis

Answer 36

congenitohereditary disorders of keratinization, distemper or leishmaniasis, pemphius foliaceus, drug reaction, DLE, zinc-responsive and generic dog food dermatosis, necrolytic migratory erytheam, cutaneous lymphoma

Question 37

What is naturally occurring vitamin A metabolized to? What is its role?

Answer 37

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*

Question 38

Is sulfur keratoplastic or keratolytic? Why?

Answer 38

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

Question 39

DDX for nasal hyperkeratosis

Answer 39

hereditary nasal hyperkeratosis of the Lab, DLE, pemphigus erythematosus