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Defect in the keratinizing epithelium or glandular function, usually due to hereditary causes or breed predilections.
primary disorders of keratinization
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The major of keratinization disorders are ______________.
secondary to another dermatosis
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What are PE findings with keratinization disorders? (7)
dry, waxy, or greasy scaling, comedones, follicular casts, alopecia, inflammation, crusts, pruritus
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How do you diagnose a primary keratinization defect?
rule out all potential causes of secondary scaling disorders!!!
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What are pruritic causes of secondary scale? (7)
FAD, atopic dermatitis, CAFR, sarcoptic mange, Cheyletiella, pyoderma, Malassezia
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What are non-pruritic causes of secondary scale? (9)
demodex, dermatophytosis, hypothyroidism, cushings, alopecia X, metabolic diseases, autoimmune diseases (pemphigus), pyoderma/ yeast (usually pruritic but always rule out, even in the absence of pruritus), neoplastic
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What are the most common canine primary keratinization disorders? (4)
zinc-responsive dermatosis, sebaceous adenitis/granulomatous periadnexal dermatitis, canine acne, canine ichthyosis
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What are the syndromes associated with zinc-responsive dermatoses?
- Syndrome I- huskies, malamutes, bull terriers; genetic; occurs at 1-3 years of age
- Syndrome II- less common; associated with an inappropriate diet
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What are clinical signs of zinc-responsive dermatosis syndrome I? (6)
- scaling, crusting, alopecia, erythema, hyperkeratotic footpads, pruritus
- [mouth, chin, eyes, ears, scrotum, vulva, prepuce, elbows]
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What are the usual locations of zinc-responsive dermatosis syndrome I? (9)
mouth, chin, eyes, ears, scrotum, vulva, prepuce, elbows, hyperkeratotic footpads
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What breeds are associated with zinc-responsive dermatosis syndrome I? (3)
huskies, malamutes, bull terriers
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How do you diagnose zinc-responsive dermatosis syndrome I? (4)
history, PE, rule out diseases that cause secondary scale, biopsy (suggestive)
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What will you likely see on biopsy of a dog with zinc-responsive dermatosis syndrome I?
marked diffuse epidermal and follicular parakeratotic hyperkeratosis (no nuclei)
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How do you manage zinc-responsive dermatosis syndrome I? (5)
oral zinc supplementation (dose split b/w BID), low dose glucocorticoids, fatty acid supplementation, treat secondary infections, keratolytic shampoos
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An inflammatory disease directed against the sebaceous glands.
sebaceous adenitis
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What is the cause and pathogenesis of sebaceous adenitis?
cornification abnormality that causes obstruction of sebaceous ducts and inflammation of the glands
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What age and breed of dog is usually affected by sebaceous adenitis? (4 breeds)
young to middle-aged; standard poodle, akita, samoyed, belgian sheepdog
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What are clinical signs of sebaceous adenitis? (5)
bilaterally symmetrical alopecia, scaling, dull brittle hairs, may progress to generalized dermatosis with tightly adherent scales and matted tufts of hair
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Where on the body does sebaceous adenitis usually begin? (5)
dorsal surfaces (head, cervical, pinnae, face), may progress to generalized
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How do you diagnose sebaceous adenitis? (3)
history/PE, rule out causes of secondary scaling, biopsy
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What do you see on biopsy of a dog with sebaceous adenitis? (2)
granulomatous inflammation at the level of the sebaceous glands, absence of sebaceous glands in advanced disease
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What is granulomatous/ pyogranulomatous periadnexal dermatitis?
the short-coat version of sebaceous adenitis; inflammatory disease directed against the entire periadnexal region with occasional destruction of the sebaceous gland
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What 2 breeds most commonly get granulomatous to granulomatous periadnexal dermatitis?
vizsla, dachshund
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What are the clinical features of pyo/granulomatous periadnexal dermatitis? (4)
annular areas of scaling and alopecia that enlarge and coalesce, intermittent edematous swelling of muzzle, lips, and eyes
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How do you treat pyogranulomatous to granulomatous periadnexal dermatitis? (4) [first choice]
topical degreaser then spray with emolliant (applied for 30 min) weekly then decreased to PRN; spray with emolliant every day; omega-3 and omega-6 fatty acids
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How do you treat pyogranulomatous to granulomatous periadnexal dermatitis? (2) [second choice]
cyclosporine (atopica), vitamin A supplement [systemic- use this method when topical only first choice treatments are not feasible for the owner (a lot of work)]
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What is the etiology of ichthyosis?
hereditary and usually congenital
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What breeds are usually associated with ichthyosis? (5)
norfolk terrier, jack russell, golden retriever, american bulldog, cavalier king charles spaniel
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How do you get a definitive diagnosis of ichthyosis?
biopsy
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Describe the ichthyosis that Norfolk terriers get. (4)
epidermolytic ichthyosis- suprabasal keratinocyte vacuolation and lysis, hypergranulosis, marked hyperkeratosis
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Describe the ichthyosis that jack russell terriers, golden retrievers, and american bulldogs get.
Non-epidermolytic ichthyosis- laminated orthokeratotoic hyperkeratosis on biopsy
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Describe clinical presentation of ichthyosis in jack russells. (4)
non-epidermolytic ichthyosis, severe, thick adherent scale, severe yeast infections
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Describe clinical presentation of ichthyosis in golden retrievers. (3)
autosomal recessive non-epidermolytic ichthyosis, large soft white adherent scaling, ventral hyperpigmentation
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Describe the clinical presentation of ichthyosis in american bulldogs. (6)
autosomal recessive non-epidermolytic ichthyosis, dissheveled coat after birth, brown adherent scale, large white scale, yeast overgrowth, +/- pruritus
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What types of ichthyosis have genetic tests?
golden retrievers, american bulldogs- autosomal recessive non-epidermolytic ichthyoses (2 different gene mutations)
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Describe the clinical presentation of ichthyosis in CKCS. (8)
congenital non-epidermolytic ichthyosis and keratoconjunctivitis sicca and ichthyosiform dermatosis, present at birth, curly hair, autosomal recessive, abnormal nail growth, orthokeratotic hyperkeratosis
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How do you treat ichthyosis in CKCS. (2)
- no successful treatment for skin- moisturizing, emollient sprays, vitamin A
- ocular treatment to prevent progression of keratitis
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What primary keratinization disorders occur in the cat? (4)
[all very rare] feline acne, feline seborrhea, sebaceous adenitis, ichthyosis
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Describe feline acne pathologic process.
idiopathic disorder of follicular keratinization (unlike canine acne, occurs in young AND adults)
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What are the clinical features of feline acne? (10)
crusts, comedones, chin/lips, may progress to papules, pustules, folliculitis, furunculosis, cellulitis, alopecia, edematous/thick
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How do you diagnose feline acne? (3)
- classic lesions (comedones)- rule out demodex, dermatophytosis, yeast/pyoderma
- culture for secondary bacterial infections
- chin edema- rule out eosinophilic granuloma with biopsy
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What do you see on biopsy of feline acne? (6)
follicular keratosis, plugging, dilatation, [if advanced] perifolliculitis, folliculitis, furunculosis
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How do you treat feline acne?
- clip fur, antiseborrheic/follicular flushing shampoo, [if papules/secondary infection] topical mupurocin 3 weeks, +/- oral antibiotics for deep infections/inflammation
- once controlled, find minimum maintenance therapy
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