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Dermatology > Demodicosis > Flashcards

Demodicosis Flashcards

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Dermatology Board Prep flashcards
1
Q

What is the life cycle of demodex?

A
  • normal inhabitant of the skin
  • obligate parasite
  • life cycle: 25-30d
    • females lay eggs in hair follicles/glands
    • eggs hatch into 6-legged larvae
    • larvae molt to 8-legged nymphs
    • nymphs molt to 8-legged adults
    • adult mites in hair follicles, sebaceous glands and sweat glands
  • feeds on cellular debris
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2
Q

How are mites transmitted?

A
  • to pups from bitch in first 1-3d of life
  • present in low #s in healthy post-natal dogs
  • dz caused by abnormal proliferation
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3
Q

What is the pathogeneiss of demodicosis?

A
  • deficient cell mediated immune response
    • involved in progression of dz
  • genetics, autosomal recessive
    • juvenile onset, generalized
  • immunosuppression
    • juvenile onset: poor nutrition, stress, estrus, endoparasites
    • adult onset: steroids, endocrine dz, neoplasia
  • Bacterial folliculitis
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4
Q

True or False: Demodicosis is contagious and zoonotic

A

false! neither contagious nor zoonotic

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5
Q

What are the clinical signs of demodicosis?

A
  • pupules/pustules, erythema
  • alopecia
  • scaling, crusting
  • comedones (follicular plugging)
  • patchy alopecia
  • hyperpigmentation
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6
Q

How do you diagnose demodicosis?

A
  • three techniques:
    • deep skin scrapes
    • hair plucks
    • biopsy:
      • Shar pei
      • Scar tissue
      • pododermatitis
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7
Q

What are the various times of onset of demodicosis for small vs. large vs. giant breeds

A
  • Small breeds: 12 mo
  • Large breeds: 18 mo
  • Giant breeds: 24 mo

* juvenile onset <; adult onset >

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8
Q

What is juvenile onset localized demodicosis?

A
  • evidence of mites in one area based on 5 deep skin scrapes –> benign
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9
Q

If you diagnose demodez on a deep scrape, what two questions should you ask?

A
  1. Is it generalized?
    • scrape 5 places total
  2. If not, will it become generalized?
    • don’t treat, wait and see
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10
Q

What are two reasons you must know if the disease will generalized?

A
  • To know/discuss prognosis
  • To make recommendations about spaying/neutering
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11
Q

What percentage of localized demodicosis will clear spontaneously vs. generalize?

A
  • Clear spontaneously (us. in 6-12 wks) = 90%
  • Generalize = 10%

good prognosis for juvenile onset localized demodicosis

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12
Q

How should you treat juveline onset localized demodicosis?

A
  • benign neglect
  • antibiotics - esp. if pustular
    • topical: 2% mupirocin, benzoyl peroxide gel/shampoo
    • systemic (if needed)
  • de-worming, good diet, HW prev, TLC
  • No steroids or anti-mite tx
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13
Q

Why shouldn’t you treat localized demodicosis with miticides?

A
  • to know if it will become generalized
  • prevent unnecessary medical tx
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14
Q

How do you tell if localized demondicosis is become generalized?

A
  • monitor the course of dz
    • recheck in 2-4 wks
    • deep skin scrape same 5 spots
      • if mite counts decr: lesion resolving, recheck q., 4 weeks until neg
      • if mite counts incr (+/-) other sites + for mites: may be progressing to generalized
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15
Q

Describe generalized demodicosis

A
  • 5 localized lesions or more
  • involvement of an entire body region (ex: the head)
  • involves 2 or more feet = pododemodicosis
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16
Q

What percent will self-clear in juvenile-onset, generalized demodicosis?

A
  • 50% will self-clear
  • 50% need anti-mite tx
    • 95% will resolve with tx
    • 5% will need life-long tx
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17
Q

Describe adult-onset generalized demodicosis

A
  • age: >1-2 yrs (breed dependent)
  • differentiate from a juvenile onset case –> never cleared or diagnosed
  • underlying immunosuppression
    • steroid misuse
    • endocrine dz
    • metabolic dz
    • neoplasia
18
Q

Define pododemodicosis

A
  • demodicosis of 2+ feet
    • generalized demodicosis
  • often chronic and resistant to therapy
19
Q

How do you treat generalized demodicosis?

A
  • miticide
  • antibiotics
    • treat secondary bacterial infections
    • until first negative scrape
  • benzoyl peroxide shampoo
    • follicular flushing
20
Q

What are 3 treatment options to kill mates?

A
  • Amitraz - Mitaban
  • Ivermectin - Ivomec
  • Milbemycin - Interceptor
21
Q

Describe Amitraz

A
  • only FDA approved tx
  • mechanism: monoamine oxidase inhibitor, alpha adrenergic agonist, inhibits prostaglandin synthesis
  • clip hair short, bathe with benzoyl peroxide shampoo before dipping
    • benzoyl shampoo - follicular flushing
  • label use: 1 vial/2 gallons H2O q 2 wks
  • in reality: dip once weekly
  • do not bathe or get wet in b/t dips
  • need gloves and ventilation
  • dip until 3 neg consecutive scrapings 2-4 wks apart
22
Q

What patients should you be concerned for when treating with Amitraz?

A
  • Toy breeds
  • sick, old patients
  • extensive ulcerations
23
Q

What are the side effects of Amitraz?

A
  • sedation/dull mentation
  • reversal agents:
    • Yohimbine
    • Atipamezole
  • avoid use in owners with:
    • asthma
    • diabetes
    • owner taking a MOA: Parkinson’s dz
24
Q

What are some causes of failure with Amitraz treatment?

A
  • steroids
  • Staph pyoderma not treated
  • concurrent dz
  • genetics
  • long hair, bath b/t dips
  • poor owner compliance
  • premature discontinuation of tx

*no improvement after 6-9 dips

25
Q

Describe Ivermectin

A
  • off label
  • use in amitraz resistant cases, animals that do not tolerate the dips
    • build up to final dose slowly
    • watch for neuro side effects
  • tx until 3 consecutive negative scrapes
26
Q

What breeds should ivermectin not be used in?

A
  • Collies/Border collies
  • Shelties
  • OESD
  • Aussies
    • “White feet don’t treat”
27
Q

What does the MDR1 gene deletion cause?

A
  • defect in protein pump (P-glycoprotein)
  • drug crosses into brain but is not pumped out efficiently
28
Q

Describe Moxidectin

A
  • Advantage multi
  • weekly or every other week application
    • systemic absorption
    • less effective than oral ivermectin but possible options for dogs that cannot take ivermectin
    • off label use of this product
29
Q

Describe Bravecto (flurolaner)

A
  • highly effective in eliminating Demodex
  • 1 pill eliminated 100% of mites by day 56
  • More effective than Advantage Multi once monthly
  • currently labeled for Demodex
  • safe for MDR1 breeds
30
Q

Describe Nexgard and Simparica

A
  • both tx are effective in killing Demodex
  • Safe for ivermectin sensitive breeds
  • oral, once a month
31
Q

How do you monitor therapy for generalized demodicosis?

A
  • DEEP skin scrape 5 sites
    • always include: Muzzle and 2 feet
  • record mite counts
  • re-scrape same sites every 4 wks
  • treat until 3 consecutive negative skin scrapes at 4 wk intervals
32
Q

What is the prognosis for generalized demodicosis?

A
  • 97% juvenile onset, generalized clear with proper tx
  • important factors:
    • proper dipping/admin of meds
    • proper skin scrapings (DEEP)
    • abx tx –> correct dose/adequate time
    • 3 neg, consecutive skin scrapes
    • clinically normal dog can be positive for rare demodex
  • Breeds difficult to clear: OESD, Afghan hound, shih tzu, lhasa apso
  • spay/neuter: heat cycle can cause incr in mite counts: do once pyoderma clears, before or at first neg skin scrape
33
Q

Describe adult onset generalized demodicosis

A
  • look for underlying cause
  • treatment options - same as juvenile onset demodex
  • px: depends - do you find the underlying cause? Can you control it?
34
Q

Describe feline demodicosis

A
  • uncommon to rare (varies geographically)
  • two species of mite:
    • D. cati and D. gatoi
35
Q

Describe demodex cati

A
  • follicular mite
  • variable pruritus
    • head and neck
  • immunosuppressed- Generalized
    • diabetes
    • FeLV/FIV
      metabolic dz
  • long and narrow
  • Dx: deep skin scrape
36
Q

Describe Demodex gatoi

A
  • Stratum corneum mite
  • contagious
  • can be very pruritic
    • trunk
    • head and neck
  • short and wide
  • common in Texas
  • Dx: superficial skin scraping
37
Q

What are the clinical features of feline demodicosis?

A
  • localized/generalized
  • alopecia
  • scaling
  • erythema
  • hyperpigmentation
  • ceruminous otitis
  • +/- pruritus
38
Q

How do you diagnose feline demodicosis?

A
  • broad SUPERFICIAL skin scrapes for D. gatoi
    • dorsal neck/lateral
    • antebrachium
    • may be difficult to find
      • parasite is superficial
      • good groomers
  • deep skin scrapes 3-5 sites for D. cati
    • localized vs. generalized
39
Q

How do you treat D. cati?

A
  • Ivermectin PO or SQ weekly x 6 wks
  • LymDyp: 1-2% lime sulfur - unknown benefit
  • Not rx: Amitraz
  • spontaneous resolution is possible
40
Q

How do you treat D. gatoi?

A
  • LymDyp: 1-2% lime sulfur
    • miticidal
    • anti-bacterial
    • anti-pruritic
  • tx all cats in contact
  • E-collar until dry to prevent:
    • oral ulcers
    • GI upset

Dermatology (13 decks)

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