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EV ACVD Study > Equine Allergy Consensus statement > Flashcards

Equine Allergy Consensus statement Flashcards

1
Q

Most common allergic trigger in horses

A

Insect bites

*Culicoides > Black fly (Simulium)

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2
Q

“Sweet itch” cause

A

Culicoides

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3
Q

IgE has been detected in horse serum after WHICH insect bites

A

*Simulium (black fly)
*Tabanidae (horse fly)
*Culicoides (midges)

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4
Q

Body distribution of culicoides

A

Varies by species, geography

*C. pulicaris on dorsum
*C. punctatus on ventral abdomen

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5
Q

Clinical signs of IBH

A

Tail swishing
Head shaking
Stamping
Skin twitching

**They DO remove most tabanids (horse fly)

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6
Q

How do horses fight off tabinids (horse fly)

A

Scratching behaviors, go to dark areas (horse flies like sun)

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7
Q

When time of day do tabanids (horse flies) prefer

A

Bright sunlight

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8
Q

During which seasons are culicoides less active

A

Winter: cold, dry

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9
Q

During which time of day are culicoides most active

A

Dust/dawn

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10
Q

T or F: anaphylaxis has occurred 2’ culicoides bite

A

FALSE. Has not been reported

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11
Q

T or F: anaphylaxis has occurred 2’ Simulium (black fly) bite

A

True. Developed shock from histamine in Simulium saliva

Anaphylaxis shock in sensitized animals

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12
Q

Which sex of Culicoides bites

A

Females– need blood to support egg production

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13
Q

Culicoides are “pool feeders”. What does that mean? Factors to help with ingestion

A

*Form a pool of unclotted blood to ingest efficiently

*Factor X: hydrolyzes prothrombin to thrombin
*Apyrase: enzyme that converts ATP (needed for platelet aggregation) to AMP (vasodilation)
*Digestive enzymes (hyaluronidaze, trypsin, chymotrypsin) to disrupt skin and connective tissue when biting; digestion of blood meal

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14
Q

Major allergens for Culicoides

A

*Cul n 1
*Cul n 2 (hyaluronidase)
*Cul n 4
*Cul n 5

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15
Q

T or F: Duration of IBH significantly affects the degree of sensitization

A

FALSE

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16
Q

Horse breed with high rate of Culicoides hypersensitivity

A

Icelandic born horses

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17
Q

Types of hypersensitivity reaction for IBH

A

Type I and Type IV (24-48hr later)

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18
Q

Which cell type is abundant in IBH skin, follicular epithelium, and intradermal sweat ducts

A

Langerhans cells
(MHC cl II, Birbeck granules)

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19
Q

Which type of T cell is higher in skin from IBH horses

A

CD4 > CD8

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20
Q

Where in the IBH horse do IL-13 and IL-4 have their effect

A

IL-13 drives inflammation in the peripheral tissue

IL-4 has a central inflammatory effect

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21
Q

Which transcription factor is downregulated in skin of IBH horses (lesional and nonlesional skin)

A

FoxP3 (TF for TRegs)

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22
Q

Which T-cell response is increased, decreased in IBH horse

A

Th2 is increased. Th1 is decreased. Treg is decreased

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23
Q

During summer, is IL-4 or IFNg increased in IBH horses?

During winter, is IL-4 or IFNg increased?

A

Summer: IL-4 is higher (Th2)

Winter: IFNg is higher (Th1)

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24
Q

T or F: microarray IgE serological tests with pure r-Culicoides allergens has high specificity and sensitivity for IBH diagnosis

A

True

Just not commercially available yet

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25
Q

An increased in _______ antibodies PRECEDES clinical signs in IBH horses

A

IgG5, IgG1

IgE levels increase CONCURRENTLY with clinical signs. Not a great predictor of a flare

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26
Q

While basophils play a role in IBH, these 2 cells characterize the skin infiltration in IBH

A

Mast cells, eosinophils

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27
Q

T or F: Blood eosinophil numbers correlate with IBH severity

A

TRUE

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28
Q

Which TYPE of Type IV hypersensitivity are eosinophils a part of

A

Type IV b

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29
Q

T or F: IL-5 plays a key role in IBH

A

TRUE
Eosinophils are a major skin infiltrate in IBH leisons

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30
Q

Which sensory nerves mediate pruritus in IBH horses

A

Unmyelinated polymodal C fibers

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31
Q

Which histamine receptors are expressed on sensory nerve endings to cause immediate itch responses

A

H1, H4

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32
Q

Which histamine receptor regulates sleep, cognitive functions

A

H3

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33
Q

Which histamine receptor is on the enterochrommaffin cells of the stomach

A

H2

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34
Q

Which histamine receptor is on lymphocytes, DCs, mast cells, eos, keratinocytes

A

H4 –> immune and inflammatory response mediator

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35
Q

Which enzyme converts amino acid histidine into histamine

A

Histidine decarboxylase

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36
Q

Other than mast cells, which 2 cells types also produce histamine in inflamed settings

A

Macrophages
Keratinocytes

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37
Q

What protein is present in mosquito saliva as an antiinflammatory?

(As opposed to Simulium, which has histamine in its saliva for vasodilation)

A

D7 proteins bind:
-Histamine
-5-hydroxytryptamine
-Thromboxane
-Cysteinyl leukotrienes

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38
Q

Function of 5-hydroxytryptamine (5-HT) at high and low doses

A

Low dose: itch
High dose: pain

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39
Q

Which vasoactive amine is responsible for pain from bee stings

A

5-HT

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40
Q

T or F: Antihistamines work well for IBH

A

FALSE.

Same efficacy as placebo

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41
Q

How does PAR-2 contribute to the itch sensation

A

Binds MRGPR on sensory nerves –> itch

42
Q

Which major itch receptors are on nociceptor nerves

A

TSLP, IL-33, IL-31

43
Q

Risk factors for IBH

A

EXPOSURE LATER IN LIFE

*Grazing outside
*Sunlight
*Climate
*Rainfall
*Vegetation
*Stabling
*Type of bedding
*Deworming frequency

44
Q

Which body regions are affected by Culicoides spp (geographics matter)

A

Pruritic papules on the: *Ears
*Face
*Chest
*Legs
*Withers
*Rump
*Tail base
*Inguinal region
*Ventral midline

45
Q

“River blindness”

A

Onchocerciasis

46
Q

What is the vector for Onchocerca cervicalis (microfilaria)

A

Culicoides

47
Q

Clinical lesions of Onchocerca cervicalis, body region

A

Microfilaria: scale, crusts, ulceration, alopecia, and depigmentation on the VENTRAL MIDLINE

Adults live in the nuchal ligament

48
Q

Treatment Onchocerca cervicalis

A

Macrocyclic lactones for microfilaria

No adulticides for adults

49
Q

What is the most common cause of equine eosinophilic granulomas

A

Insect bites

50
Q

T or F: Horses can develop hyperreactive airways 2’ IBH

A

True

51
Q

T or F: Horses with IBH also have concurrent environmental allergies

A

True

52
Q

Which is better: IDST vs Serum for IBH

A

Good agreement

53
Q

Most effective treatment for IBH

A

Insect avoidance

-move away from standing water
-stable horses at night
-use fans

(if needed, use systemic GCs)

54
Q

Fly sprays that are effective

A

Permethrin
DEET

(Citronella, cypermethrin were NOT)

55
Q

What topical product can help with IBH skin lesions (but not pruritus)

A

*Cream with OFA3, humectants, emollients

56
Q

T or F: high dose N-3 fatty acids can help with IBH pruritus and skin lesions

A

FALSE. No significant effect (but possible flaw with the study. OFA was from flax-seed. Can try algae/fish)

57
Q

What is the mast cell INHIBITORY receptor

A

FCgRIIb

ASIT shifts Th2-> Th1, IgG blocks binding of IgE to allergens, prevents mast cell degranulation by binding to FcgRIIb

58
Q

Combining Culicoides crude extract with _____ may make ASIT more effective

A

Mycobacterial cell wall fraction (immunostimulant)

59
Q

Is ASIT with current commercial extracts recommended for IBH treatment?

A

Evidence is lacking. Hoping for improvement with recombinant vaccines

60
Q

2 vaccine targets for IBH horses

A

IL-5
IL-31

61
Q

Horse breeds predisposed to Atopic Dermatitis

A

*Arabians
*Finn horses
*Thoroughbreds

62
Q

Skin barrier defects in horses with Atopic Dermatitis

A

*Alterations in lipid lamellae
-Retained lamellar bodies

*Altered phospholipid profiles
-lower levels of phosphatidylcholine and spingomyelin

63
Q

Atopic Dermatitis in horses: top 3 clinical signs

A

1) Urticaria
2) Pruritus
3) Urticaria + Pruritus

64
Q

Location of pruritus for Atopic Dermatitis in horses

A

Face, trunk, flexural surfaces

+/- urticaria

65
Q

Most common triggers for urticaria in horses

A

Food
Bug
Drug
environmental allergens
Oral supplements
Vaccines

66
Q

Age of onset for Atopic Dermatitis in horses

A

Any age
Consider geographical moves

67
Q

Most common positives on IDT in horses

A

Culicoides
Dermatophagoides farinae

68
Q

Withdrawal time for oral glucocorticoids and antihistamines before IDT in horses

A

Antihistamine: 1 week
Glucocorticoids: 14 days

69
Q

Is IDT or serum testing better for Atopic Dermatitis in horses

A

Both are good– good correlation

70
Q

Reasons why prednisolone > prednisone in horses

A

*Poor absorption
*Rapid excretion
*Failure of hepatic conversion of prednisone to prednisolone via 11-B hydroxysteroid dehydrogenase

71
Q

Which steroid is most likely to trigger laminitis in horses

A

Triamcinolone

(also steroid hepatopathy)

72
Q

Reason glucocorticoids may trigger laminitis

A

*Vasoconstriction
*Increased circulating insulin or glucose
*Decreased collagen production in lamellae
*Diminished keratin production in hoof wall
*Diminished growth of coronary band

73
Q

Which horses are most likely to develop laminitis 2’ steroid administration

A

Those with predisposing factors (breed, weight, endocrinopathy)

74
Q

What is the most common adverse effect of hydroxyzine in horses

A

Sedation

75
Q

MOA of pentoxifylline

A

*Synthetic xanthine derivative

*Inhibits phosphodiesterase

ALLERGY: inhibits T and B cell activation, increase IL-10, PGE2, decrease leukocyte adhesion, decrease neutrophil superoxide, degranulation, IFNg, NK cell activity

*Rheological effects
*Improves wound healing (Increased fibroblast collagenases, decrease TNFa)

76
Q

What diseases is pentoxifylline used for in horses

A

Endotoxemia
Laminitis
Airway disease

77
Q

Which topical glucocorticoid is not absorbed systemically in horses

A

Hydrocortisone aceponate (Cortavance)

Use for mane/tail pruritus short term

78
Q

Which eicosinoid was decreased after using fish oil supplementation in a horse

A

Prostaglandin E2

n-3 OFAs can decrease IDST!

79
Q

Effect of Apoquel on horses with atopic dermatitis

A

Decreased pruritus, no change on skin lesions

Unlicensed in horses

SID dosing

80
Q

Time to improvement with ASIT in horses

A

As early as 2 months!

81
Q

Efficacy of ASIT in horses

A

70% improve

2/3 stay in remission after ASIT d/c

82
Q

Impact of ASIT on level of Tregs, TGFb, IL-10, IFNg in horses

A

No change after 1 year!

83
Q

Impact of ASIT on IgE levels in horses

A

Decreased at 6 months, but increased at end of study

84
Q

Which cases of atopic dermatitis in horses could receive autoserum

A

Autoserum separation, so abnormal aggregate complexes of lipids are dissolved –> allows normalization of cell signaling.

70% of horses respond per owners

85
Q

Environmental changes that can minimize horse Atopic Dermatitis flares

A

*Change bedding from straw to low-dust cardboard
*Change feed (avoid hay) to pelleted diet. OR immerse hay in water to minimize dust
*Ventilation in stables
*Move hourse from indoor to pasture (minimize dust, mites, mold)

*Wash bedding– HDM on blankets
*Storage mites on mouldy bedding, hay

86
Q

CAFR triggers in horses

A

Oats
Pasture
Pasture plants

But consider everything

87
Q

Which food should be avoided if suspicious of CAFR horse

A

High protein grasses (alfalfa, peanut hay)

88
Q

Which foods have triggered urticaria

A

Peanut hay
Garlic supplements
Concentrated foods

89
Q

How long until improvement is noted for CAFR in hroses

A

*Usually within a few days
*Recommend 4+ weeks

90
Q

T or F: serologic tests for food are great in horses

A

False

91
Q

T or F: positive IDST to hays is highly suspicious of a CAFR in horses

A

False. Could be epicutaneous exposure

92
Q

T or F: urticaria is always a type I hypersensitivity

A

False. Reports of Type II and III hypersensitivities. IgG against IgE (rather than an allergen)

93
Q

Non-hypersensitivity triggers for urticaria in horses

A

*Exercise
*Physical stimuli (dermatographism)
*Thermal stimuli
*Psychogenic stress

Cholinergic “Sweat-induced” Urticaria

94
Q

Which cytokines are upregulated in urticarial skin in horses

A

IL-4
IL-13
TSLP
IL-4ra

95
Q

Where on the body do urticaria typically occur

A

Neck, sides, face

96
Q

T or F: Urticaria are always pruritic

A

Not always pruritic

97
Q

Differential for urticaria in horses

A

Erythema multiforme

98
Q

T or F: Horses with urticaria have more positive IDST reactions

A

True

99
Q

Treatments for urticaria in horses

A

Glucocorticoids, antihistamines

Consider pentoxifylline and OFA for chronic cases

100
Q

T or F: diphenhydramine is readily available in the horse

A

False. Poor bioavailability. Need injectables.

EV ACVD Study (52 decks)

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