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Dermatology > Ectoparasites > Flashcards

Ectoparasites Flashcards

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Dermatology Board Prep flashcards
1
Q

Fleas love

A

humidity

colorado have lower prevalence

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2
Q

What species is the common cat flea

A

Ctenocephalides felis

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3
Q

What is the primary lesion of an ectoparasite infestation

A

papule

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4
Q

Flea bite hypersensitivity is a reaction to

A

the flea allergen

burden does not equate with severity

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5
Q

What is the distribution of fleas

A

“Pants sign” -the caudodorsum of the animal

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6
Q

How can fleas present in cats

A

reaction pattern- eosinophilic granuloma/plaques, military dermatitis, indolent ulcers

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7
Q

How do you diagnose fleas

A

Combing
1) Flea dirt
2) actual observation of fleas variable- flea-nial?
they live off the host

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8
Q

What parasiticides are very toxic to cats *

A

Permethrins

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9
Q

What are different parasiticides

A

1) Permethrins- never for cats, only repellants
2) Neonicotinoids- bind to insect a-ch inhibition
Imidacloprid, dinotefuran, sinetoram/spinosad, nitenpyram
3) Phenylpyrazole
4) Avermectin- chloride channel agonists
5) Oxadiazine- blocks Na channels
6) Insect growth inhibitors (methoprene, lufenuron, pyriproxyfen)

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10
Q

How do you chose what type of parasiticide to give

A

-Effiacy
-Adverse Effects
-Ease of Use
-Cost
-Compliance

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11
Q

What is the mechanism of action of Isoxazolines (Bravecto, Nexgard, Simparica, Credelio)

A

potent inhibitor of y-aminobytyric acid (GABA)- gated chloride channels and L-glutamate gated chloride channels

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12
Q

What is the gold standard for flea treatments

A

Isoxazoline parasites (Bravecto, nexgard, simparica, credelio)
-kills 98%+ of fleas within 24 hours to halt the population
-adulticides preferred but IGRs can be supplementary
-1-2 months for resolution of flea allergic signs

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13
Q

How you you treat fleas

A

1) Isoxazoline parasites (Bravecto, nexgard, simparica, credelio)
-kills 98%+ of fleas within 24 hours to halt the population
-adulticides preferred but IGRs can be supplementary
-1-2 months for resolution of flea allergic signs

2) Use allergy meds

3) Topicals- pyrehtroid shampoos/sprays can help patient during eradication
sprays/vacuuming can help environment
foggers of limited use

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14
Q

What is the goal of tick control

A

Prevention of disease transmission - not eradication

no tick product kills ticks instantly (takes 48h for 90% kill)
disease transmission takes long time

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15
Q

What causes alpha-gal syndrome

A

A. americanum (lone star tick)

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16
Q

Isoxazolines kill fleas within _________ and have a _______ kill rate
kill ticks in about _____ and have a ______ kill rate

A

Fleas: kill within 24 hours and 98% rate
Ticks: kill within 48 hours and have 90% kill rate

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17
Q

What is the most pruritic dog disease

A

Sarcoptes scabei var. canis

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18
Q

Mange is a

A

mite infestation

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19
Q

What is the distribution of Sarcoptes scabei

A

Elbow
Distal limbs (carpi, tarsi)
Pinnae

they like the hairless/short hairs areas

this indication is very indicative of sarcoptes
rarely otitis occurs on pinnae
very pruritic

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20
Q

When Sarcoptes scabei is chronic you see

A

severe hypertrichosis and crusting of the distal pinnae

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21
Q

Why might sarcoptes scabei not cause pruritus in all animals in the house

A

one dog might not be hypersensitive to the bites

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22
Q

T/F: sarcpotes scabei is communicable between dogs and humans

A

True

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23
Q

How do you diagnose sarcoptes

A

*hard to find
1) Superficial skin scrapes (surface mites)
40% positive scrapes in confirmed cases
Pinnal-pedal reflex?

dont use ELISA

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24
Q

How do you treat Sarcoptes

A

On-label: Revolution (selamectin) month or Advantage multi (moxidectin) monthly

off-label: ivermectin, libemycin, doramectin, fipronil spray, amitraz, lime sulfur

Routine washing/vacuuming fine 2x weekly but mite is not long-lived in the environment
treat. patient symptomatically but often resistant to antipruritics

treat for 8 weeks- consider contagious for treatment duration

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25
Q

What species are resistant to sarcoptes

A

cats and horses

self-limiting in humans

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26
Q

T/F: Cheyletiellosis is zoonotic

A

True

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27
Q

Cheyletiellosis is the walking

A

dandruff

28
Q

Is lice species specific

A

Yes

29
Q

T/F: Cheyletiellosis is species specific

A

False- not necessarily

30
Q

Cheyletiellosis is commonly transmitted in

A

high density and immunocompromised populations

31
Q

Cheyletiellosis has what distribution

A

usually a dorsal distribution (scaly)

32
Q

How do you diagnose Cheyletiellosis

A

Superficial scrapes
Flea combing
acetate tape preps

33
Q

How do you treat Cheyletiella?

A

Same as Sarcoptes
-Ivermectin
-Salmectin
-Milbemyin
-Fipronil spray
-Lime sulfur (weekly)
-Treat for 8 weeks as a generic guidline

34
Q

T/F: Demodex spp are contagious

A

False- they are not contagious but there are rare exceptions

35
Q

Why is Demodex not a parasite

A

1) Disease of immunosuppression and overgrowth
youre suppose to have Demodex, just not a bunch of them
also they are species specific and not contagious

36
Q

T/F: Demodex is a commensal organism

A

True- not a parasite, disease of immunosuppression and overgrowth

37
Q

What are the two types of Demodecosis

A

1) Juvenile- immune system hasnt developed yet. lesions- alopecia, erthyema, papular dermatitis, folliculitis, collarettes
will resolve with immune maturity (localized) also generalized form

2) Adult-Onset: Immunocompromised (steroids, endocrine, neoplasia, apoquel, stress)- Generalized

38
Q

What is the lifecycle of Demodex

A

1) Eggs (football-shaped, fusiform), hatch after 3-4 days
2) adult in a week (juvenilles 6 legs, adults 8)
3) Total lifecycle is 2-4 weeks

39
Q

What is the classical presentation of Demodectic Mange

A

Diffuse alopecia, erythema, papules (and secondary crusts), comedones
demodex likes the face/eyes (more sebaceous glands)

40
Q

What are the top 3 differentials for follicultis

A

1) Bacterial pyoderma
2) Dermatophytosis
3) Demodicosis

41
Q

Adult onset Demodex

A

Always considered generalized
Always treat
Look for source of immunocompromise

42
Q

What causes adult-onset Demodex

A

1) Immunomodulating drugs (Apoquel, steroids)
2) Endocrinopathies
3) Neoplasia
4) Stress

43
Q

What species that if you see Demodex on them, it is very seriouds

A

Cat and Horses

44
Q

What Demodex species is considered contagious

A

D. gatai - (surface mite) in the cats

not associated with immunosuppression

45
Q

Cats have to be _____________ for Demodex cati

A

extremely immunocompromised

46
Q

How do you diagnose Demodex

A

One mite with compatible clinical signs
-Deep skin scrapings (follicular*)
-Hair plucks (100 hairs)
-Exudate (purulent, cerumen)
-Acetate tape (more sensitive?)
-Gatoi: very difficult to find (fecals?)

dont diagnose by response to therapy

47
Q

What is a less invasive way to find Demodex than a deep skin scrape

A

Trichogram- pluck 100 hairs (not as sensitive but easier and less invasive)

Acetate tape (more sensitive) with squeezing the skin, specifically the eggs and nymphs

48
Q

Demodex can be via fecal flotation especially in

A

cats- groomers

49
Q

How do you on-label treatment for Demodectic mange

A

On-label: Amitraz (Mitaban)
antagonistic effect on octopamine receptors of the nerve cells in the brain
topically every 2 weeks for 3-6 treatments

causes sedation (central alpha-adrenoreceptor agonist)
hair clipping

50
Q

What is the on-label treatment for Demodex, although not often used

A

Amitraz (Mitaban)
antagonistic effect on octopamine receptors of the nerve cells in the brain
topically every 2 weeks for 3-6 treatments

causes sedation (central alpha-adrenoreceptor agonist)
hair clipping

51
Q

What is the mechanism of action of macrocyclic lactones (ivermectin, selamectin, moxidectin, doramectin, milbemycin)

A

stimulation of glutamate and GABA-gated chloride channels

52
Q

macrocyclic lactones (ivermectin, selamectin, moxidectin, doramectin, milbemycin) should not be used in what dogs

A

those with the MDRI (ABCB1) mutation

might be able to tolerate 3x daily dosing

53
Q

How has demodectic mange historically been treated

A

macrocyclic lactones (ivermectin, selamectin, moxidectin, doramectin, milbemycin)
stimulate glutamate and GABA-gated chloride channels
typically daily therapy
Cats- lime sulfur dips weekly

54
Q

What is the MDR-1 (ABCB1) gene mutation

A

a gene mutation that results in incomplete p-glycoprotein synthesis; important component of blood barrier- drug efflux pump (prevents ivermectin from accumulating in the brain)
Homozygous- toxicity
common in Australian Shepherds, border collies, german shephard

55
Q

How is demodectic mange treated today

A

Isoxazolines!
can also combine with a macrocyclic lactone

56
Q

What is a common ectoparasite in large animals

A

Chorioptes - like long hairs

tx: ivermectin, topical fipronil and lime sulfur weekly
isoxazoline?

57
Q

what is the ear mite

A

Otodectes cynotis

58
Q

How do you treat otodectes cynotis

A

three doses required? ISmparica
resolived in 14 days with Bravecto (cat topical)
All others two monthly doses recommended

59
Q

Pediculosis is infestation of

A

Lice

60
Q

What are the chewing lice

A

Dogs: Trichodectes canis
Cats: Felicola subrostrata

61
Q

What species is the dog sucking louse

A

Linognathus setosus

62
Q

Unlike fleas, lice live

A

on the host

63
Q

T/F: lice are species specific

A

True

64
Q

How do you treat pediculosis in horses

A

use topicals (pyrethroids lime sulfur, fipronil)

65
Q

Isoxazoline products have been associated with

A

Neurologic adverse reactions
- muscle tremors
-ataxia
-seizures

but very rare and self-limiting (only a few days)

66
Q

what should you do for culicoides hypersensitivity in horses

A

Must reduce exposure to butes of biting midges
stable at night
fans
blankets/coverings
pyrethrins/pyrethroids

sometimes steroids, antihistamines (insect-bite hypersensitivity/allergy)

67
Q
A

Dermatology (10 decks)

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