23.11.1: Pruritic ectoparasite disease Flashcards

1
Q

Aetiopathogenesis of Flea Allergy Dermatitis

A
  • Hypersensitivity (Type I or Type IV) to salivary proteins of the flea
  • Leads to self-trauma by pet
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2
Q

True/false: if only one animal in a household is affected, FAD is automatically lower down on the differential diagnoses list.

A

False
* The house may be infested with fleas but it is possible that only one animal is hypersensitive to flea saliva.
* Therefore, it is perfectly possibly for other pets not to be showing clinical signs.

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3
Q

Clinical signs of FAD in dogs

A
  • Scratching
  • Biting skin
  • Jumping up suddenly
  • Excess licking/overgrooming
  • Alopecia
  • Skin inflammation ± skin infection
  • Crusting
  • Lichenification
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4
Q

Which areas of the dog’s body are typically affected in FAD?

A
  • Caudal half of body (tail base, thighs, inguinal area)
  • Dorsum
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5
Q

What disease might this pattern make you suspicious of and why?

A

Flea Allergy Dermatitis
* Caudal half of body (tail base, thighs, inguinal area), dorsum

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6
Q

Which drugs are active against environmental life cycles (larvae, eggs) and adult fleas?

A
  • Imidacloprid
  • Selamectin
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7
Q

Which drugs are effective against adult fleas?

A
  • Imidacloprid
  • Selamectin
  • Dinotefuran
  • Permethrin, flumethrin, tetramethrin
  • Fipronil
  • Pyripole
  • Nitenpyram
  • Isoxazolines
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8
Q

What are some examples of insect growth regulators (IGRs) effective against flea eggs and larvae?

A
  • Pyriproxifen
  • (S)-methoprene
  • Lufenuron
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9
Q

Which drugs are effective against adult fleas, but not against eggs or larvae?

A
  • Dinotefuran
  • Permethrin, flumethrin, tetramethrin
  • Fipronil
  • Pyriprole
  • Nitenpyram
  • Isoxazolines
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10
Q

What flea control measures are there?

A
  • Mechanical removal e.g. flea combing, vacuum cleaning
  • Repellants
  • Adulticides
  • Larvicides
  • Ovicides
  • Insect growth regulators (these may be juvenile hormone analogues or chitin synthase inhibitors)
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11
Q

How long is the flea life cycle?

A

3-4 weeks
Can range from 2 weeks - 6 months depending on environmental conditions

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12
Q

Clinical signs of FAD in cats

A
  • Head and neck pruritus
  • Miliary dermatitis
  • Bilaterally symmetrical alopecia due to overgrooming
  • Eosinophilic granuloma complex lesions (eosinophilic plaques, eosinophilic granulomas, indolent ‘rodent’ ulcers)
  • i.e. any of the cutaneous reaction patterns of the cat
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13
Q
A

Indolent ulcers

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14
Q

Diagnosis of FAD

A
  • Demonstration of fleas on the animal + compatible clinical signs (negative finding is unreliable)
  • Intradermal and serological testing - limited value
  • Response to therapy - best method of diagnosis is by response to thorough flea control trial
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15
Q
A

Cat with FAD

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16
Q

How long might it take to fully eliminate fleas from the animal and environment?

A

3 months

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17
Q

1 and 2

A
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18
Q

Which species should you not give fipronil to?

A

Rabbits

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19
Q

Which species should you avoid using permethrins in? What is the exception to this?

A

Cats
Flumethrin is fine

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20
Q

When should you be cautious about using isoxazolines?

A

If the patient has a history of seizures

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21
Q

a) Advantage (imidacloprid)
b) Advantix (imidacloprid + permethrin)
c) Frontline combo (fipronil + S-methoprene)
d) Simparica (sarolaner)

A

d) Simparica (sarolaner)

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22
Q

1

A
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23
Q

2

A
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24
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3

A
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25
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4

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26
Q

1

A
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27
Q

2

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28
Q

3

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29
Q

4

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30
Q
A

Trichodectes canis
This is a canine sucking louse

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31
Q
A

Linognathus setosus
This is a canine chewing louse

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32
Q
A

Felicola spp.
This is a feline chewing louse

33
Q

What is the difference between a chewing louse and a biting louse?

A

They are the same thing

34
Q

Where does the louse life cycle take place? How long can they survive off a host?

A
  • Whole life cycle on host -> easy to kill!
  • Adults survive for only 3 days off the host
  • May have nits in bedding -> indirect infestation
35
Q

True/false: lice are species-specific but contagious within that species.

A

True

36
Q
A

Louse egg a.k.a. nit attached to hair
These have an operculum (lid) that is circled in the image

37
Q

Clinical signs of lice infestation

A
  • Pruritus, crusting, erythema, scaling, alopecia
  • Sometimes asymptomatic
  • Heavy infestations can lead to anaemia in puppies and small dog breeds
  • Trichodectes can act as intermediate host to the dog tapeworm Dipylidium caninum
  • Reaction to bites from Felicola subrostratus can resemble miliary dermatitis
38
Q

Diagnosis of lice

A
  • Coat combing/ brush
  • Hair plucks for eggs
39
Q

Treatment of lice

A
  • Many flea adulticides effective e.g. imidacloprid, fipronil, selamectin
  • Isoxazolines are not licensed but likely effective
  • Treat in contacts
  • Clean the environment
40
Q
A

Sarcoptic mange in a dog

41
Q
A

Sarcoptes scabiei var canis

42
Q
A

Sarcoptes eggs and faeces

43
Q

Where are Sarcoptes found - on the surface vs burrowing vs deep?

A

They burrow in the stratum corneum

44
Q

Where does the Sarcoptes life cycle take place and how well can they survive off the host?

A
  • Entire life cycle on host
  • Can survive off host for limited period 48-72hrs
  • Widlife reservoir = foxes
45
Q

True/false: Sarcoptes is neither contagious nor zoonotic.

A

False
Sarcoptes is highly contagious and zoonotic‼️

46
Q

Clinical signs of Sarcoptes

A
  • Severe pruritus - focuses on elbows, hocks, ear pinna, ventral chest
  • Erythematous papules with a greyish-yellow exudate
  • Lesions spread rapidly covering entire body
  • Self-trauma results in severe excoriation, lichenification and patchy alopecia
  • Can develop secondary infection and lymphadenopathy
  • 80% show pinnal pedal reflex
47
Q

Diagnosis of Sarcoptes

A
  • Skin scrapings - high risk of false negatives. Need to be deep!
  • IgG ELISA serology is available but rarely used; false +ves and -ves and serocoonversion takes 4 weeks
  • Therapeutic trial if diseases suspected
48
Q

Treatment of Sarcoptes

A
49
Q
A

Cheyletiella spp.

50
Q
A

Cheyletiella spp.

51
Q

True/false: Cheyletiella are host-specific and contagious.

A

False
Cheyletiella are non host-specific and they are very contagious.
They are also zoonotic‼️

52
Q
A

Cheyletiella eggs

53
Q

Where does the Cheyletiella life cycle take place and how long can they survive off the host?

A
  • Life cycle on host
  • Can survive for 10+ days off host
54
Q

Clinical signs of Cheyletiella spp

A
  • Pruritus
  • Papular and crusted lesions (miliary dermatitis in cats) esp on dorsum and trunk
  • Dry scaling or flaking
  • Some affected animals have no signs and can be carriers
55
Q

Diagnosis of Cheyletiella spp

A
  • Superficial skin scrape
  • Microscopy of scale from combing -> in liquid paraffin under coverslip
  • Unstained acetate tape strip on skin
  • Trichogram for eggs
  • Trial treat if suspected - false negatives are common
56
Q

True/false: some Cheyletiella spp affect rabbits

A

True

57
Q

Treatment of Cheyletiella

A
  • Hard - can survive off host
  • Treat affected animal and in contacts
  • No licensed products but isoxazolines, selamectin and moxidectin effective
  • Clean environment and use environmental flea spray
58
Q
A

Otodectes
Otodectes infestation is called otoacariasis

59
Q

Where does the life of Otodectes take place?

A
  • In the ears
  • Other areas of the body can be a reservoir
  • Life cycle = 21 days
  • Can survive off host depending on environmental conditions
60
Q

Which of the following apply to Otodectes ?
* Host specific
* Contagious
* Zoonotic

A

Otodectes is contagious!
It is not zoonotic. It is not host-specific.

61
Q

Clinical signs of Otodectes

A
  • Intense pruritus and head shaking
  • Thick dark brown exudate
  • Miliary dermatitis in cats
62
Q

Diagnosis of Otodectes

A
  • Ear swab
  • Microscopy
  • Otoscopic examinations
63
Q

Treatment of Otodectes

A
64
Q
A

Neotrombicular autumnalis (harvest mite)

65
Q

Where does the harvest mite life cycle take place?

A
66
Q

Which species can harvest mites affect?

A
  • Dogs
  • Cats
  • Occasionaly humans

Not host-specific.
Not directly contagious between people or zoonotic but people can be infested from larvae from the ground.

67
Q

Clinical signs of harvest mites

A
  • Papules
  • Crusts
  • Pruritus
  • Especially seen in interdigital space, pinnae (Henry’s pocket), ventral abdomen
68
Q

Diagnosis of harvest mites

A
  • Visual ID
  • Coat comb/brushing
  • Unstained acetate tape strip
  • Superficial skin scrape
69
Q

Treatment of harvest mites

A
  • No licensed products
  • Options: fipronil every 2 weeks / selamectin spot-on/ Isoxazolines likely effective
70
Q

Which of these two parasites is variably pruritic and which is highly pruritic?
Demodex canis
Demodex injai

A

Demodex injai - highly pruritic (thankfully less common)
Demodex canis - variably pruritic but common

71
Q
A

Demodex canis

72
Q
A

Demodex injai

73
Q

Which parasite does this apply to?

A

Demodex injai

74
Q

Clinical signs of Demodex cati

A
  • Localised demodicosis is rare can also present as a ceruminous otitis externa
  • Pruritus variably - generally absent to mild
  • Crusting
  • Alopecia
  • Mild erythema
  • May also see lichenification and hyperpigmentation
75
Q
A

Demodex cati

76
Q

What is this and how will you find it on the animal?

A

Demodex gatoi
* Superficial skin scrapes from areas inaccessible to tongue - unlike other Demodex which are deep this one lives in the superficial stratum corneum

77
Q

Clinical signs of Demodex gatoi

A
  • Pruritus
  • Generalised overgrooming and self trauma
  • Underlying skin may be erythematous (red mange) amd mildly scaly
  • Comedomes may be present
78
Q

Treatment of Demodex cati, Demodex gatoi

A
  • Localised form may be self-limiting
  • No licensed products: sarolaner, fluralaner
  • Address underlying cause
  • For Demodex gatoi treat in-contacts also
79
Q

A 4 y.o. Boxer presents with dorsal pruritus and scale. What are your top 2 differentials?
a) demodicosis, cheyletiellosis
b) sarcoptic mange, cheyletiellosis
c) flea allergic dermatitis, sarcoptic mange
d) flea allergic dermatitis, cheyletiellosis
e) demodicosis, flea allergic dermatitis
f) demodicosis, sarcoptic mange

A

d) flea allergic dermatitis, cheyletiellosis