Hypersensitivity 1 Flashcards

1
Q

What is the main immunoglobulin (antibody) involved in type 1? Function?

A

IgE
- involved in allergies and parasite infections

Triggers inflammation bc it exists pre-bound to basophils and mast cells
- cause them to degranulate when they bind to their antigen

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2
Q

Exaggerated hypersensitivity type 1 responses are the common cause of?

A

Allergies

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3
Q

Why do hypersensitivity type 1 reactions occur?

A

some animals produce more IgE
- dogs

some antigens produce very strong IgE responses
- wasp and bee stings (naturally programmed to create response, excessive IgE makes more severe)

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4
Q

Why are hypersensitivity type 1 reactions considered immediate?

A

IgE is pre-bound to mast cells

- created a rapid response to allergens (minutes)

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5
Q
Mast cells (sentinel) use IgE as a detection mechanism
Example of when IgE response is appropriate
A

Internal parasitic worms activate mast cells

Mast cells release chitinase
- destroy parasite’s outer covering and attracts eosinophils to destroy them

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6
Q

Describe the mechanism of activation of mast cells/basophils/eosinophils due to IgE
What are the signs of this occurring?

A

IgE pre-bound to these cells
- when appropriate allergen binds to IgE, causes mast cell to degranulate

Release interleukin 31
- sensitizes and stimulates pruritis

Release histamine and heparin
- vasodilation and increased capillary impermeability

Attracts eosinophils

Signs: redness, pale MM, swelling (local edema), itchiness

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7
Q

Atopy definition

A

The genetic predisposition to allergic disease (type 1)

Affected animals often have increased production of IgE and become sensitized to allergens common to the environment

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8
Q

What breeds are more susceptible to allergic diseases?

Which ones are less susceptible?

A

More: terriers, dalmatians, retrievers

Less: none pure bred dogs

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9
Q

Describe the 3 main causes of allergic skin disease (atopic dermatitis)
Give an example of each

A

Contact with environmental allergen (skin keratin defect )
- people a metal allergy

Injected allergen
- flea saliva, culicoides/midge bites in horses - sweet itch, mosquitoes

Ingested allergen (food)

  • small amount of dietary protein from gut is absorbed intact
  • may or may not have GI signs, absorbed allergen may travel through the blood and bind to skin mast cells
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10
Q

What are the signs of allergic skin disease (atopic dermatitis)?

A

Often first seen in younger adults

Pruritis (intense itching in the feet and ears often first sign)

Skin lesions/changes (hives/urticaria)

Erythema (red skin)

Scratching/licking feet or rubbing
- damages skin (alopecia, thickening - hyperkeratosis, pigmentation)

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11
Q

Describe hives/urticaria

A

Raised lumps

Small or large

Warm, edematous

Pruritic

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12
Q

How is allergic skin disease (atopic dermatitis) diagnosed?

A

Exclusion in the diet or environment: allergies

  • cut out possibilities one at a time before diagnosing allergy
  • time consuming

Skin testing: environmental allergies
- inject potential allergens into the skin an see if there is a reaction (patches)

Serum testing: better at ruling things out

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13
Q

How is allergic skin disease (atopic dermatitis) treated?

A

Washing/bathing frequently

  • contact dermatitis*
  • tepid/cool water and moisturizing shampoos (oatmeal = anti-pruritic)

Reduce inflammation
- antihistamines, corticosteroids, atopica (cyclosporin), oclacitinin (apoquel), monoclonal antibody (reduces itching)

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14
Q

How is allergic skin disease (atopic dermatitis) prevented?

A

Remove source or allergen
(environmental changes, reduce flea infestation, stables horses to avoid midges, diet changes)

Dietary exclusions (feed a simple diet, novel proteins, test different proteins)

Changing to less inflammatory diet (increase omega-3 fatter acids - fish/flax/canola)

Desensitization (allergy shots, aim is to switch Ig synthesis to IgG, gradually increase doses)

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15
Q

Is evening primrose oil helpful in allergic skin disease?

A

No

contains omega-6 fatty acids (not omega-3)

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16
Q

What is similar about hay fever and asthma?

What is the difference?

A

both IgE mediated hypersensitivities of the resp tract

Difference depends on where the antigen is trapped

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17
Q

Medical term for hay fever

A

Allergic rhinitis

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18
Q

Large particles get trapped in the upper airways cause?

A

Hay fever

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19
Q

Small particles carried down into the lungs cause?

A

Asthma

20
Q

T or F

Hay fever is mainly a people problem

A

True

21
Q

Signs of hay fever

A

Nose: sneezing, watery nasal discharge, blocked passages, itchy nose

Eyes: itchy, red, swollen, feel gritty, blueness bellow skin (only people)

Throat: soreness, itchy

Sleep: mouth breathing and fatigue

22
Q

Who is asthma seen in

A

Cats
Basenji dogs
People

23
Q

Asthma signs

A

Wheezing
Dyspnea

Can be acute or severe and even fatal

24
Q

How is asthma diagnosed?

A

Administrating a bronchodilator

- if it works then bronchoconstriction is causing the problem

25
Q

Hay fever and asthma is less likely in humans if

A

Lots of siblings and we raised on a farm

26
Q

Asthma and hay fever more likely if

A

There is a family history

27
Q

What are seasonal allergies often caused by?

A

Pollen from any type of plant or spores from fungi

28
Q

What are year round allergies usually caused by?

A
Dust mites 
Roaches (produce allergen) 
Animal dander 
Fungi 
Molds
29
Q

Dander allergens are more of a concern when

A

Working indoors

30
Q
T or F 
Fine dander (cats and rabbits) are more likely to cause hay fever/asthma
A

True

31
Q

Main allergen found on cats

A

Salivary protein that sticks to hair when licking

32
Q

T or F

There is a diet that contains antibodies against common cat salivary allergens to help reduce reactions in people

A

True

33
Q

What is anaphylactic shock?

A

An extreme, life threatening allergic reaction to an allergen

34
Q

When is anaphylactic shock a major concern?

A

Giving a biological product (vaccine) due to injection of an actual antigen or live virus

Penicillin (common)

35
Q

How long does it take for an anaphylactic shock reaction to occur?

A

15-30 minutes

36
Q

What should vet practices always have on hand in case of anaphylactic shock?

A

Epinephrine
Antihistamines
Corticosteroids

37
Q

Describe when major anaphylactic shock signs are seen and in what species

A

Lungs AND GI: horses
Lungs only: cattle, sheep, cats
GI only: dogs

38
Q

What species may anaphylactic reactions be seen in the skin?

A

Cats

39
Q

Why are the kidneys and skeletal muscles not affected in anaphylaxis?

A

Mast cells are driving the anaphylactic response and are only found at entry points of the body (GI and lungs)

These areas have few sentinel cells

40
Q

What are some common respiratory signs of anaphylaxis?

A

Increased RR
Dyspnea
Coughing

41
Q

What are some common GI signs of anaphylaxis

A

Vomiting (not in horses)

Increased defecation/diarrhea (may be bloody)

42
Q

What are some other signs of anaphylaxis?

A

Skin irritation (cats) and scratching around head

Weakness
Incoordination
Collapse
Death

43
Q

Antihistamines are used in treatment of anaphylaxis in?

A

Antihistamines: diphenhydramine (Benadryl)

Give 2.2mg/kg

Often used in early signs

44
Q

Why should antihistamines not be given in food/orally?

A

Takes longer to absorb

Patient may be vomiting or have diarrhea

45
Q

What does epinephrine do in the treatment of anaphylaxis?

A

Stabilizes mast cells and stops degranulation

Reverses vasodilation

Dilates smooth muscle to help breathing

Rapidly absorbed if given IM or SQ

Dose for cats and dogs is 0.1 - 0.5 ml or 1:1000 epinephrine solution

46
Q

What are some commonly used IV fluids to support circulation and help treat anaphylaxis?

A

Corticosteroids
Prednisolone sodium succinate
Dexamethasone phosphate in water

47
Q

A patient came in and got a first time vaccine along with a booster vaccine
Ended up having a severe allergic reaction and came back to clinic
What is the most likely cause of the reaction? Why?

A

The booster vaccine (not the first time vaccine) because the immune system/body has been primed against the vaccine that was boosted at the first vaccination appointment so the reaction was ready the second time

The first time vaccine would not have created a reaction so fast because the immune system has not been previously primed against it