Parasitic Skin Disease Flashcards

1
Q

What are the 3 types of parasites (host-parasite relationship? Give an example of each?

A
  1. ticks
  2. fleas
  3. demodex
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2
Q

What class are the following parasites:
Demodecosis, Demodecosis, Cheyletioellosis, Trombiculiasis

A

Arachnids

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3
Q

Which animal(s) does demodex prefer?

A

Dogs&raquo_space;> Cats > Horses

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4
Q

Which animals does sarcoptes (scabies) prefer?

A

DOGS

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5
Q

Which animals does cheyletiellosis prefer?

A

Dogs > Cats

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6
Q

Which animals does trombiculiasis prefer?

A

Dogs, Cats and Horses all equally affected

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7
Q

Which animals typically have flea bite hypersensitivity?

A

Cats and dogs

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8
Q

What is trombiculiasis caused by? What is usually visible on the dog (what life stage). What seasons is it most common in? What is the range of the symptoms?

A

Caused by (Neo)Trombicula autumnalis (Mite)
Larvae just visible
Strictly seasonal (July-Sept/Oct)
Asymptomatic —> Pruritic (range)

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9
Q

T or F - Some dogs are more susceptible to parasites than others

A

T

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10
Q

What is happening here?

A

Trombiculiasis (mite) larval stage attaches to dog, stay on for a day or two, then drop off to continue life cycle in the environment
Some dogs have an extreme reaction to the mites (erythema, irritation, pruritis, inflammation) while some dogs have no reaction at all

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11
Q

What is the treatment for Tombiculiasis? What do you need to combine pharmacology with?

A

None licensed - Fipronil, Possibly Avermectins/Isoxazolines
Need to combine treatment with anti-itch medication and reduce exposure to mites

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12
Q

What is happening here?

A

Dog from racing kennels
Spent time in kennels + moved to foster home with 9 other dogs
Heavy mite infestation, but not itchy or inflamed

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13
Q

What is this parasite?

A

Cheyletiella - Surface fur mite

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14
Q

What is cheyletiellosis? Is this a zoonosis?
What animals is it typically seen in?

A

Infection of the skin by:
- Cheyletiella blakei
- Cheyletiella yasurgi
- Cheyletiella parasitivorax
ZOONOTIC
Seen in dogs, cats, rabbits, guinea pigs

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15
Q

What are the clinical signs of cheyletiellosis?

A

scaling (walking dandruff)
Typically affects trunk
Pruritis (mild&raquo_space; severe)
Primarily dorsal trunk
Cats - miliary dermatitis

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16
Q

What is the treatment protocol for cheyletiellosis? How easy is this to achieve? Who else should you treat besides the animal affected?

A

Treat with medication + clean environment
Must treat ALL animals in contact with affected animal
No licensed medications, but typically use:
- Amitraz (dog)
- Fipronil (dog, cat)
- Selamectin (dog, cat)
- Moxidectin (dog, cat)
- Isoxazolines (dog, cat)
- Ivermectin (cat, rabbit)

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17
Q

How did this happen? What is this cluster of lesions called?

A

Mites do not live on people, but will bite people if come onto the skin (such as from carrying rabbit on bare arm)
Once infection on pet is cleared up, bites no longer a risk for human

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18
Q

What is this condition?

A

Comedones

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19
Q

What is this condition?

A

Comedones

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20
Q

What is happening in this scanning electron microscope image? What are the red arrows pointing to?

A

Demodex mites (red arrows) within hair follicle

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21
Q

How would you sample these demodex mites?

A

Either scrape this region with 10 blade
Or pull out hair (taking demodex along with it) and look under microscope

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22
Q

Is demodex a commensal organism? How does demodex infection occur?

A

YES
Parasite burden becomes too much for animal for whatever reason and balance between parasite and host becomes altered

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23
Q

define “demodecosis”

A

An inflammatory parasitic skin disease characterized by the presence of larger than normal numbers of demodectic mites

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24
Q

which species of demodex are common in the dog? Which of these is the long-bodied mite?

A

D. canis
D. injair (long-bodied mite)

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25
Q

Which species occur in the cat? How common are these? Which of these are contagious?

A

Uncommon/rare
D. cani (similar to D. canis)
D. gatoi (short bodied mite - contagious, pruritis)

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26
Q

what are the 3 factors necessary for demodecosis?

A
  1. More than commensal amount of demodex
  2. inflammation
  3. pruritis
27
Q

What does it mean if you recover demodex mites on skin scraping?

A

Indicates imbalance in host/parasite relationship
If you SEE demodex on skin scraping that means populations of mites are VERY high
Usually do not recover any mites on healthy individuals (even though they are there)

28
Q

What are the 3 manifestations of demodecosis?
Which of these often recovers spontaneously?

A

Juvenile onset, localized - often recovers spontaneously
Juveile onset, generalized
Adult onset, localized or generalized

29
Q

What is the difference between juvenile onset generalized and localized demodecosis?

A

localized - usually no treatment needed, animal’s own immune system will keep mite numbers in check and infestation will typically resolve
generalized - host cannot keep numbers in check, usually develops from localized infection, might have genetic predisposition

30
Q

What is not recommended to do with animals who have juvenile onset generalized demodecosis? Why?

A

Do not breed from them - might pass on genetic predisposition to demodecosis

31
Q

How is juvenile onset demodecosis usually contracted?

A

By contact with the dam

32
Q

How does adult onset demodecosis occur? What is the typical age of onset? What should you suspect in these patients?

A

Suspect immunosuppression
True adult onset >2 years of age
Host parasite relationship has changed for some reason and its your job as the vet to work out why
Could be due to drugs (glucocorticoids), endocrinopathy, neoplasia

33
Q

What are the 3 dog breeds who commonly have both juvenile and adult onset demodecosis?

A

Chinese Shar-Pei
Pug
Boxer

34
Q

What is the recommended therapy for generalized demodecosis cases? What should you absolutely NOT prescribe?

A

Therapy of choice - Isoxazolines (Fluralaner - Bravecto) - one dose needed
Unauthorized (but inexpensive) - Ivermectin
AVOID STEROIDS AND OCLACITINIB (APOQUEL)
- Even in self-trauma cases

35
Q

How should you monitor patients with demodecosis? How long should you treat? How many weeks minimum treatment should you expect?

A

Monitor by clinical exam and repeat scrapes/plucks
Treat until 2 negative samples taken at least 14 days apart
Expect minimum 12 weeks of treatment

36
Q

What is happening in this case? What went wrong in treatment?

A

Patient treated with steroids resulting in deep bacterial infection secondary to demodecosis
AVOID steroids in demodecosis because skin must return mite populations to normal homeostasis on its own. If immune system is subdued the mite burden will be too much once the medication is taken away (vicious cycle)

37
Q

What is this condition called?

A

Pruritis

38
Q

What is this?

A

Sarcoptes (burrowing mite)

39
Q

What is sarcoptic mange? What is another name for it? Which animal is it common in? Which animal is it rare in? What is important to know about equine infestations?

A

Canine scabies - an intensely pruritic, transmissible infestation of dogs caused by sarcoptes scabiei
Common in dogs
Rare in cats
Very rare in horses (notifiable)

40
Q

Which types of cats usually contract scabies infestations?

A

Immunosuppressed

41
Q

What are these lesions caused by? Why is this such a good site to sample?

A

Lesions created by burrowing mite sarcoptes

Want to scrape the scales and crusts OFF THE EAR and cause it to bleed a bit to expose the mites/eggs/feces

Especially good chances of seeing the mites if it is a site where the animal could not reach to bite or lick (ears are great place)

42
Q

Label this photo

A
43
Q

What parasite infestation has this typical presentation?

A

Fleas

44
Q

Describe the flea life cycle

A
45
Q

What are the mechanisms involved in ectoparasite hypersensitivity?

A

IgE mediated (mast cell activation)
Delayed cell mediated
- Basophil hypersensitivity
- TH1 (macrophage activation)
- TH2 (lymphocyte/eosinophil activation)

46
Q

What is ectoparasite hypersensitivity in dogs/cats similar to in another animal?

A

Sweet itch in horses

47
Q

Do antihistamines work for ectoparasite hypersensitivity?

A

Not really - not only an IgE mediated process, other things involved

48
Q

What are the various antigens which can cause ectoparasite hypersensitivity to occur?

A

Saliva, Cuticule, Excreted metabolites/enzymes/toxins, Feces

49
Q

How does flea bite hypersensitivity occur? What is the antigen that animals are sensitive to?

A

Animals sensitized to flea salivary antigens
Multiple cat saliva antigens
Major allergen >90% flea allergy dermatitis dogs reactive

50
Q

What type of hypersensitivity reaction is flea bite hypersensitivity?

A

Immediate and/or delayed intradermal reaction

51
Q

What is the typical age of onset for flea allergy hypersensitivity?

A

3-5 years

52
Q

What increases the chance of an animal developing flea allergy hypersensitivity?

A

Possible breed predisposition
Atopic dogs predisposed (presence of other allergic skin disease)
Seasonal

53
Q

What is this?

A

Flea Allergy Dermatitis

54
Q

What is this? Why is this an atypical presentation?

A

Flea Allergy Dermatitis
Typically on dorsum, rather than ventrum, but this case is very severe

55
Q

How do you diagnose flea bite hypersensitivity?

A

History and signs
Evidence of flea bite exposure
- Presence of fleas/feces (wet paper test)
- not always easy to find
Response to therapy
Allergy testing

56
Q

How accurate is intradermal testing (whole body extract) for immediate/delayed reactions in dogs vs. cats? What % of normal cats will test +ve?
Should you recommend that people use this testing?

A

Dogs:
Up to 24% normal dogs +ve in flea-rich environments
Sensitivity 30-70%, Specificity 80-90%
Cats:
Sensitivity 33%, Specificity 78%
Up to 30% normal cats +ve

Not recommended - low sensitivity/specificity, false positives, potentially many false negatives, might waste client’s money

57
Q

What is the sensitivity/specificity of FceRla-based flea saliva specific serology in dogs and cats?
Should you recommend this test?

A

Dog - Sensitivity 97%, specificity 53%
Cat - overall accuracy 82%

Not recommended - low sensitivity/specificity, false positives, potentially many false negatives, might waste client’s money

58
Q

Do all animals with flea allergy hypersensitivity have a high flea burden?

A

No - might become sensitized by just one or two bites

59
Q

what are the 2 main principles in flea bite hypersensitivity management?

A

Avoidance of flea bites
Antipruritic/Anti-inflammatory medication

60
Q

How do you implement “avoidance of fleas” when treating flea bite hypersensitivity?

A

Management changes
CLEAN ENVIRONMENT
Flea control regimen (all dogs in household)

61
Q

What types of antipruritics/anti-inflammatories should you give animals with flea bite hypersensitivity?

A

Glucocorticoids
Apoquel
Cytopoint
Antihistamines (to treat intense itching)

62
Q

What is this evidence of?

A
63
Q

What is this evidence of?

A
64
Q

What has developed here and what is this a result of?

A