Demodicosis Flashcards
(40 cards)
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
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
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
4
Q
True or False: Demodicosis is contagious and zoonotic
A
false! neither contagious nor zoonotic
5
Q
What are the clinical signs of demodicosis?
A
- pupules/pustules, erythema
- alopecia
- scaling, crusting
- comedones (follicular plugging)
- patchy alopecia
- hyperpigmentation
6
Q
How do you diagnose demodicosis?
A
- three techniques:
- deep skin scrapes
- hair plucks
- biopsy:
- Shar pei
- Scar tissue
- pododermatitis
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 >
8
Q
What is juvenile onset localized demodicosis?
A
- evidence of mites in one area based on 5 deep skin scrapes –> benign
9
Q
If you diagnose demodez on a deep scrape, what two questions should you ask?
A
- Is it generalized?
- scrape 5 places total
- If not, will it become generalized?
- don’t treat, wait and see
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
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
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
13
Q
Why shouldn’t you treat localized demodicosis with miticides?
A
- to know if it will become generalized
- prevent unnecessary medical tx
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
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
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
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
Describe Ivermectin
* 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
What breeds should ivermectin not be used in?
* Collies/Border collies
* Shelties
* OESD
* Aussies
* "White feet don't treat"
27
What does the MDR1 gene deletion cause?
* defect in protein pump (P-glycoprotein)
* drug crosses into brain but is not pumped out efficiently
28
Describe Moxidectin
* 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
Describe Bravecto (flurolaner)
* 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
Describe Nexgard and Simparica
* both tx are effective in killing Demodex
* Safe for ivermectin sensitive breeds
* oral, once a month
31
How do you monitor therapy for generalized demodicosis?
* 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
What is the prognosis for generalized demodicosis?
* 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
Describe adult onset generalized demodicosis
* look for underlying cause
* treatment options - same as juvenile onset demodex
* px: depends - do you find the underlying cause? Can you control it?
34
Describe feline demodicosis
* uncommon to rare (varies geographically)
* two species of mite:
* D. cati and D. gatoi
35
Describe demodex cati
* follicular mite
* variable pruritus
* head and neck
* immunosuppressed- Generalized
* diabetes
* FeLV/FIV
metabolic dz
* long and narrow
* Dx: deep skin scrape
36
Describe Demodex gatoi
* Stratum corneum mite
* contagious
* can be very pruritic
* trunk
* head and neck
* short and wide
* common in Texas
* Dx: superficial skin scraping
37
What are the clinical features of feline demodicosis?
* localized/generalized
* alopecia
* scaling
* erythema
* hyperpigmentation
* ceruminous otitis
* +/- pruritus
38
How do you diagnose feline demodicosis?
* 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
How do you treat D. cati?
* Ivermectin PO or SQ weekly x 6 wks
* LymDyp: 1-2% lime sulfur - unknown benefit
* **Not rx: Amitraz**
* spontaneous resolution is possible
40
How do you treat D. gatoi?
* 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
