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
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.
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
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
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
6
Q
Which drugs are active against environmental life cycles (larvae, eggs) and adult fleas?
A
- Imidacloprid
- Selamectin
7
Q
Which drugs are effective against adult fleas?
A
- Imidacloprid
- Selamectin
- Dinotefuran
- Permethrin, flumethrin, tetramethrin
- Fipronil
- Pyripole
- Nitenpyram
- Isoxazolines
8
Q
What are some examples of insect growth regulators (IGRs) effective against flea eggs and larvae?
A
- Pyriproxifen
- (S)-methoprene
- Lufenuron
9
Q
Which drugs are effective against adult fleas, but not against eggs or larvae?
A
- Dinotefuran
- Permethrin, flumethrin, tetramethrin
- Fipronil
- Pyriprole
- Nitenpyram
- Isoxazolines
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)
11
Q
How long is the flea life cycle?
A
3-4 weeks
Can range from 2 weeks - 6 months depending on environmental conditions
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
13
Q
A
Indolent ulcers
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
15
Q
A
Cat with FAD
16
Q
How long might it take to fully eliminate fleas from the animal and environment?
A
3 months
17
Q
1 and 2
A
18
Q
Which species should you not give fipronil to?
A
Rabbits
19
Q
Which species should you avoid using permethrins in? What is the exception to this?
A
Cats
Flumethrin is fine
20
Q
When should you be cautious about using isoxazolines?
A
If the patient has a history of seizures
21
Q
a) Advantage (imidacloprid)
b) Advantix (imidacloprid + permethrin)
c) Frontline combo (fipronil + S-methoprene)
d) Simparica (sarolaner)
A
d) Simparica (sarolaner)
22
Q
1
A
23
Q
2
A
24
Q
3
A
25
4
26
1
27
2
28
3
29
4
30
*Trichodectes canis*
This is a canine sucking louse
31
*Linognathus setosus*
This is a canine chewing louse
32
*Felicola spp.*
This is a feline chewing louse
33
What is the difference between a chewing louse and a biting louse?
They are the same thing
34
Where does the louse life cycle take place? How long can they survive off a host?
* 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
**True/false:** lice are species-specific but contagious within that species.
**True**
36
Louse egg a.k.a. nit attached to hair
These have an operculum (lid) that is circled in the image
37
Clinical signs of lice infestation
* 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
Diagnosis of lice
* Coat combing/ brush
* Hair plucks for eggs
39
Treatment of lice
* Many flea adulticides effective e.g. imidacloprid, fipronil, selamectin
* Isoxazolines are not licensed but likely effective
* Treat in contacts
* Clean the environment
40
**Sarcoptic mange in a dog**
41
*Sarcoptes scabiei var canis*
42
*Sarcoptes* eggs and faeces
43
Where are *Sarcoptes* found - on the surface vs burrowing vs deep?
They burrow in the stratum corneum
44
Where does the *Sarcoptes* life cycle take place and how well can they survive off the host?
* Entire life cycle on host
* Can survive off host for limited period 48-72hrs
* Widlife reservoir = foxes
45
**True/false:** *Sarcoptes* is neither contagious nor zoonotic.
**False**
*Sarcoptes* is highly contagious and zoonotic‼️
46
Clinical signs of *Sarcoptes*
* 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
Diagnosis of *Sarcoptes*
* 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
Treatment of *Sarcoptes*
49
*Cheyletiella* spp.
50
*Cheyletiella* spp.
51
**True/false:** *Cheyletiella* are host-specific and contagious.
**False**
*Cheyletiella* are non host-specific and they are very contagious.
They are also zoonotic‼️
52
*Cheyletiella* eggs
53
Where does the *Cheyletiella* life cycle take place and how long can they survive off the host?
* Life cycle on host
* Can survive for 10+ days off host
54
Clinical signs of *Cheyletiella* spp
* 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
Diagnosis of *Cheyletiella* spp
* 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
**True/false:** some *Cheyletiella* spp affect rabbits
**True**
57
Treatment of *Cheyletiella*
* 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
*Otodectes*
Otodectes infestation is called otoacariasis
59
Where does the life of *Otodectes* take place?
* 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
Which of the following apply to *Otodectes* ?
* Host specific
* Contagious
* Zoonotic
*Otodectes* is contagious!
It is not zoonotic. It is not host-specific.
61
Clinical signs of *Otodectes*
* Intense pruritus and head shaking
* Thick dark brown exudate
* Miliary dermatitis in cats
62
Diagnosis of *Otodectes*
* Ear swab
* Microscopy
* Otoscopic examinations
63
Treatment of *Otodectes*
64
*Neotrombicular autumnalis* (harvest mite)
65
Where does the harvest mite life cycle take place?
66
Which species can harvest mites affect?
* 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
Clinical signs of harvest mites
* Papules
* Crusts
* Pruritus
* Especially seen in interdigital space, pinnae (Henry's pocket), ventral abdomen
68
Diagnosis of harvest mites
* Visual ID
* Coat comb/brushing
* Unstained acetate tape strip
* Superficial skin scrape
69
Treatment of harvest mites
* No licensed products
* Options: fipronil every 2 weeks / selamectin spot-on/ Isoxazolines likely effective
70
Which of these two parasites is variably pruritic and which is highly pruritic?
*Demodex canis*
*Demodex injai*
*Demodex injai* - highly pruritic (thankfully less common)
*Demodex canis* - variably pruritic but common
71
*Demodex canis*
72
*Demodex injai*
73
Which parasite does this apply to?
*Demodex injai*
74
Clinical signs of *Demodex cati*
* 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
*Demodex cati*
76
What is this and how will you find it on the animal?
*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
Clinical signs of *Demodex gatoi*
* Pruritus
* Generalised overgrooming and self trauma
* Underlying skin may be erythematous (red mange) amd mildly scaly
* Comedomes may be present
78
Treatment of *Demodex cati, Demodex gatoi*
* Localised form may be self-limiting
* No licensed products: sarolaner, fluralaner
* Address underlying cause
* For *Demodex gatoi* treat in-contacts also
79
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
**d) flea allergic dermatitis, cheyletiellosis**
