Dermatology - Atopic Dermatitis Flashcards Preview

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Flashcards in Dermatology - Atopic Dermatitis Deck (93)
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1
Q

Atopic dermatitis, also known as allergic inhalant dermatitis, has a ______ predisposition.

A

familial (hereditary)

2
Q

What are the major pathologic mechanisms associated with atopic dermatitis?

A

type I hypersensitivity and disruption/damage to the epidermal barrier

3
Q

What is type I hypersensitivity mediated by?

A

IgE and subclasses of IgG

4
Q

How does an animal become sensitized to an allergen?

A

An initial exposure to the antigen is required, then later exposure will lead to a reaction

5
Q

What specific molecule plays a big role in pruritus due to atopic dermatitis?

A

interleukin-31

6
Q

On a cellular level, what has been found in atopic patients?

A

they have been shown to have a cellular defect that allows increased adherence of bacteria to keratinocytes leading to increased bacterial infections

7
Q

What allergens are known to cause atopic dermatitis?

A

pollens, molds, house dust mites, epidermals (wool, feathers, horse, human), insects, and many others (like tobacco)

8
Q

What allergens typically appear in the spring?

A

trees and molds

9
Q

What allergens typically appear in the summer?

A

grasses, and some weeds

10
Q

What allergens typically appear in the fall?

A

weeds and molds

11
Q

What allergens typically appear in the winter?

A

indoor allergens (dust mites, molds)

12
Q

What allergens are typically year-round?

A

indoor allergens and combinations of the seasonal ones

13
Q

At what age does atopic dermatitis typicall present?

A

9 months - 3 years of age

14
Q

What is the hallmark of atopy?

A

pruritus

15
Q

What are some signs of pruritus?

A

licking the feet, rubbing the fase, perineal pruritus, and generalized scratching

16
Q

How do atopic lesions initally present?

A

mild: erythema, papules, and mild alopecia

17
Q

What lesions are associated with chronic atopy?

A

lichenification, hyperpigmentation, and generalized alopecia

18
Q

What areas are typically effected with atopy?

A

thin-skinned regions, such as the feet and between the toes, around the eyes, and in the axilla and inguinal regions

19
Q

What is a common manifestation of atopy?

A

otitis externa

20
Q

How may cats with allergic disease present?

A

they may have miliary dermatitis or other ‘reaction patterns of cats’ and generalized pruritus

21
Q

What often perpetuates atopic dermatitis?

A

secondary infections

22
Q

What secondary infections are commonly associated with atopic dermatitis?

A

superficial pyoderma and Malassezia dermatitis

23
Q

What are secondary infections frequently the cause of?

A

apparent’ treatment failure of atopics: so-called ‘prednisone resistance’

24
Q

Aside from secondary manifestations, otitis externa, and pruritus, what are some other clinical manifestations of allergy?

A

chronic anal sac inflammation and pruritus, acral lick dermatitis, and interdigital dermatitis

25
Q

What are some diagnostic tools to diagnosing atopic dermatitis?

A

history, physical findings, dermatologic data base, allergy tests

26
Q

What are the indications for allergy tests?

A

To confirm the diagnosis and to provide informtation for alternative therapy

27
Q

What is intradermal skin testing?

A

Injection of known amounts of allergens intradermally and comparing the reaction to a positive (histamine) and negative control (saline)

28
Q

What can be used for chemical restraint during intradermal skin testing?

A

only injalants, xylazine, dexdomitor, and some narcotis (no phenothiazines)

29
Q

What is the technique for intraderma skin testing?

A
  1. Injections are made in the lateral thoracolumbar area after gentle clipping 2. No skin preparation 3. Area can be marked with a felt-tipped pen 4. Injection of 0.05 ml of antigen intradermally with a 25-gauge needle
30
Q

When do you read the results from intradermal skin testing?

A

Reactions are read at 0, 15, and 30 minutes

31
Q

How do you prepare a patient for intradermal allergy testing?

A

No antihistamines 1-2 weeks prior, no oral glucocorticoids for a minimum of 4 weeks, no injectable glucocorticoids for 1-3 months, no otic, topical, or opthalmic glucocorticoids for 2+ weeks prior, and no fatty acid supplements and/or off diets with high concentrations of fatty acids for 2 weeks prior

32
Q

What is measured in intradermal allergy tests?

A

the degree of each reaction - erythema and wheal

33
Q

What is a considered a positive result?

A

a reaction that is greater than 2+ on the scale of 0-4+

34
Q

What is a 4+ on the scale?

A

histamine reaction

35
Q

What does a positive result mean?

A

animal is allergic to antigen, allergen is irritative to the skin, and dermohraphia

36
Q

What does a negative result mean?

A

animal is not allergic to the antigen, poor technique, drug inhibition, insufficient antigen as in mixed preparations, or an out-dated antigen

37
Q

What techniques are used in serologic allergy tests?

A

radio-allergosorbent test (RAST) or ELISA techniques to measure allergen specific IgE levels in serum

38
Q

False positives are common with what serologic allergy test?

A

RAST

39
Q

With allergy testing, what must you ask yourself?

A

Do the test results fit the patients clinical features? And Do they make sense in correlation with severity of clinical signs, seasonality, and response to therapy?

40
Q

What is the most important step to do first when treating atopic dermatitis?

A

control of perpetuating factors

41
Q

What are the types of therapies for atopic dermatitis?

A

topical therapies, antihistamines, fatty acid supplements, glucocorticoids, cyclosporine, Oclacitnib, IL-31 Monoclonal andibody therapy, and/or hyposensitization

42
Q

What is topical therapy indicated for?

A

to control the signs of allergies, especially pruritus

43
Q

What are some topical therapies for atopic dermatitis?

A

colloidal oatmeal, colloidal oatmeal + others, topical glucocorticoids

44
Q

How much relief does colloidal oatmeal allow for?

A

about 24-36 hours of relief from pruritus

45
Q

What can colloidal oatmeal be combined with?

A

Diphenhydramine HCL, Pramoxine, and hydrocoritzone

46
Q

Are topical glucocorticoids effective?

A

typically no, due to the generalized nature of the condition

47
Q

Which topical glucocorticoid may be effective as an intermittent adjunctive therapy of atopic animals?

A

Hydrocortisone shampoo

48
Q

What is the risk with overjudicious use of topical glucocorticoids?

A

it may cause iatrogenic hyperadrenocorticism and H-P-A supression leading to comedones, cutaneous atrophy at site of application, and calcinosis cutis

49
Q

How often are antihistamines helpful?

A

in 15-30% of atopic animals - will reduce pruritus by 10-90%

50
Q

What adverse effects are associated with antihistamines?

A

sedation, trembling, panting, or occasional excitement

51
Q

What is the goal of using fatty acid supplements for atopic dermatitis therapy?

A

It is intended to promote production of non-inflammatory prostaglandins in lieu of those inducing inflamation - they are thought to modulate the arachidonic acid pathways, leading to production of prostaglandins and leukotrienes that competitively inhibit receptors

52
Q

What percentage of patients have shown clinical improvement with fatty acid supplements?

A

15-30%

53
Q

When are fatty acid supplements thought to be the most useful?

A

as adjunctive therapy when used in combination with either antihistamines or glucocorticoids

54
Q

What type of glucocorticoids should be used for atopic dermatitis therapy?

A

only short acting oral glucocorticoids - prednisone, prednisolone, and methylprenisolon - long acting ones should not be used

55
Q

What is the recommended protocol for using glucocorticoids?

A

give once daily initially to control clinical signs (1.1 mg/kg), then the dose is reduced and switched to alternate-day administration (1.1 mg/kg)

56
Q

What is the recommended maintenance dosage for glucocorticoids?

A

0.5 - 1.1 mg/kg

57
Q

What are the main side effects of glucocorticoid use?

A

polydipsia/polyuria, polyphagia, and panting

58
Q

What is the generic name of cyclosporine that is used to treat atopic dermatitis?

A

Atopica and Atopica for cats

59
Q

What is the goal of cyclosporine?

A

To control pruritus by regulating cellular mechanisms, thus repress activation of immune cell types known to be involved in atopic disease

60
Q

What is the recommended dosage and protocol for use of cyclosporine?

A

5 mg/kg daily for induction 3-6 weeks, then either every other day or every day at 2.5 mg/kg

61
Q

What is the success rate of using cyclosporine?

A

65-75%

62
Q

What adverse effects are associated with cyclosporine?

A

vomiting, diarrhea, papillomatosis, and gingival hyperplasia

63
Q

What are the disadvantages to using cyclosporine?

A

high cost of treatment, considered contraindicated in patients with neoplasia

64
Q

What is the brand name of Oclacitinib?

A

Apoquel

65
Q

How does apoquel work?

A

It is an IL-31 inhibitor, classified as a Janus-kinase-1 inhibitor

66
Q

What remedies has Apoquel been shown to do?

A

reduce pruritus in animal models of atopy, in canine patients with atopic dermatitis, and in dogs with flea allergy dermatitis

67
Q

Does Apoquel work quickly?

A

Yes, but it requires twice daily therapy for induction with once daily treatment for maintenance because it has a short duration of action

68
Q

In what percentage patients is Apoquel effective?

A

in 70% of patients

69
Q

What dogs should not get apoquel?

A

dogs under the age of 1

70
Q

What adverse effects are associated with the use of Apoquel?

A

GI disturbances, weight gain, tendency to develop benign cutaneous masses

71
Q

What drug is used for IL-31 monoclonal antibody therapy?

A

Cytopoint

72
Q

How often is Cytopoint given and what does it do?

A

Once montly via injection and it is intended to bind to IL-31 before it can reach JAK-STAT receptors

73
Q

What is the duration of action of Cytopoint?

A

The average is approximately 30 days, but can be longer in some patients

74
Q

What is the advantage of using Cytopoint?

A

the advantage is that this therapy eliminates the daily fluctuations in drug concentrations that lead to variable effectiveness day to day

75
Q

When is hyposensitization indicated?

A

if symptomatic therapy alone is ineffective, when the patient has unacceptable side-effects to symptomatic therapy, when the client chooses to treat the cause

76
Q

What does hyposensitization appear to keep under control bettar than drugs that work by suppressing itch ?

A

it appears to be more effective at keeping perpetuating conditions under control than drugs that work by suppressing itch

77
Q

What is the mechanism of action of hyposensitization?

A

Formation of IgG against the antigen to prevent cross-bridging of IgE bound to mast cells

78
Q

How does hyposensitization work?

A

Antigen is induced in increasing doses to reduce sensitivity over time

79
Q

What is the success rate of hyposensitization?

A

60-80%

80
Q

How are antigens/allergens administered during hyposensitization?

A

typically subcutaneously, but can be given sublingually

81
Q

What adverse reactions are associated with hyposensitization?

A

pruritus, wheals, urticaria, erythema, and anaphylaxis

82
Q

What is the number 1 reason for atopic dermatitis ‘relapses’?

A

Malassezia dermatitis (not treated properly)

83
Q

What are some other reasons for relapse?

A

inadequate doses, poor owner and patient compliance

84
Q

When are you most likely to chose glucocorticoids for treatment?

A

When you need a rapid response, need anti-inflammatory effects, if it is needed seasonally or short-term, and if cost is a factor

85
Q

When are you less likely to chose glucocorticoids for treatment?

A

concurrent health issues, patient cannot tolerate (historically), if you plan to allergy test

86
Q

When are you more likely to chose cyclosporine?

A

Small dog (cause of cost), and some anti-inflammatory effect is desired and GCs aren’t an option

87
Q

When are you less likely to chose cyclosporine?

A

concurrent infections, diabetes mellitus, cost is a factor

88
Q

When are you more likely to chose Oclacitinib (Apoquel)?

A

need rapid response, prior to allergy testing, while waiting for immunotherapy, cost is somewhat a factor

89
Q

When are you less likely to chose Oclacitinib (Apoquel)?

A

long term use, does not provide 24 hours of relief

90
Q

When are you more likely to use Lokivetmab (Cytopoint)?

A

client compliance is an issue, convenience factor, adverse effects to other options

91
Q

When are you less likely to use Lokivetmab (Cytopoint)?

A

clients are not mobile, large dogs (cost)

92
Q

When are you more likely to chose immunotherapy?

A

younger dog, infectious/otitis are main manifestation, owners prefer to treat the disease vs masking symptoms

93
Q

When are you less likely to chose immunotherapy?

A

Client compliance/ability to administer treatment, owners want/expect short term gratification

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