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What ingredients of topical medications (esp. otic) are widely implicated in contact dermatitis? (2)
neomycin, propylene glycol
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What are common components of a history with contact dermatitis?
corticosteroid responsive, with allergen one animal affect/with irritants all animals affected
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What are the 2 types of contact dermatitis?
- with allergen one animal affect
- with irritants all animals affected
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Clinical signs of contact dermatitis? (9)
highly pruritic, poorly haired areas (ventrum, scrotum, axillae, medial pinnae, mouth, interdigital), erythema, exudation, papules, crusting/scaling, alopecia, hyperpigmentation/ lichenification, well-demarcated
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What lesions are commonly associated with contact dermatitis? (7)
- Primary: erythema, papules
- Secondary: exudation, crusting, scaling, alopecia, hyperpigmentation/ lichenification
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How do you diagnose contact dermatitis? (3)
- rule out AD, CAFR, and parasites
- treat secondary infections
- bathe and board for 1-2 weeks (get out of home environment)
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How do you treat/manage contact dermatitis? (3)
- avoidance (if you can ID cause)
- glucocorticoids
- pentoxifylline
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How do you rule out AD when diagnosing contact dermatitis?
- although body sites are similar, contact dermatitis is limited to unhaired body regions and it is well-demarcated, whereas AD does not stay to specifically unhaired areas
- Also, contact dermatitis has primary lesions (papules), which are NOT seen with AD
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What are the "3 P's" that cause canine acral lick dermatitis (lick granuloma)?
- primary causes: boredom/stress, psychogenic, allergic dz, focal stimulus, foreign body, neuropathy, endocrinopathy
- predisposing factors: change in environment, new pet, change in routine, anxiety, inadequate exercise, clipping fur
- Perpetuating factors: bacterial infection, keratin FB, fibrosis, osteomyelitis/arthritis, learned behavior
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What is the itch-lick cycle?
lick--> endorphin release--> euphoria
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What breeds usually get lick granulomas?
large breeds- doberman, great dane, rott, retriever, GSD
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Describe the lesions of lick granuloma. (7)
cranial carpal, tarsal, metatarsal alopecia-->firm ulcers--> hard, pigmented, nodular, NON-PAINFUL
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What are differentials for a nodular, ulcerated plaque on the distal limb of a dog? (4)
lick granuloma, neoplasia (mast cell tumor), nodular dermatitis, demodicosis
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What is the diagnostic approach for lick granuloma? (6)
FNA, biopsy (histopath + culture- deep infection), radiographs, measure lesion, if suspect underlying allergies- work up for allergies, if suspect metabolic (thyroid)- blood work
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How do you treat lick granulomas? (4)
ID/treat primary cause, control secondary deep infection (long course of antibiotics), decrease inflammation, behavior modification
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What topical therapies are commonly used for lick granulomas? (3)
- glucocorticoids- synotic (flucinolone in DMSO, carrying it deep into the tissue)
- NSAIDs
- analgesics (capsaicin- if neuopathy)
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What systemic therapies are commonly used with lick granulomas?
- Tricyclic antidepressant drugs: Doxepin (also antihistamine properties), Clomipramine
- Selective serotonin reuptake inhibitors: Fluoxetine (psychogenic, neuropathic lickers)
- Serotonin antagonist reuptake inhibitors: Trazodone
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