Allergy

Question 1

What is an allergy?

Answer 1

An inappropriate immune response to harmless foreign antigen can be systemic or loaclised

Question 2

What are the mechanisms of allergic reactions?

Answer 2

Type I: Immediate type - mast cell degranulation mediator releases
Type IV: Delayed type - activation of macrophages via cytokines

Question 3

What are Ultcaria, Angioedema and Anaphalylaxis?

Answer 3

Ultcaria - Dermal wheals and maybe pruritus
Angioedema - Subcutaneous tissues involved - usually swelling of the eyelids lips
Anaphylaxis - Systemic mast cell degranulation and histamine release

Question 4

What therapy is available for systemic hypersensitivity? how are these administered?

Answer 4

• Antihistamines, steroids, and epi-pen (epinephrine)
• Often administered intravenously or orally in antihistamines case

Question 5

What is allergic skin diseases and give examples of different types of allergic skin diseases?

Answer 5

Type I hypersensitivity (sometimes type IV in case of allergic contact dermatitis) - types include flea allergic dermatitis, atopic dermatitis, feline eosinophilic granuloma complex, sweat itch in horses

Question 6

What is flea-allergic dermatitis?

Answer 6

• Type 1 hypersensitivity to flea saliva - dogs will scratch and cats will overgroom both causing hair loss

Question 7

What is canine atopic dermatitis?

Answer 7

Allergic reaction to environmental allergens such as pollen causing dogs to be very itchy - could cause secondary trauma often resulting in an oppurtunistic infection

Question 8

What is sweat itch in horses?

Answer 8

Allergic reaction to midge bites often affecting the dorsum and tail base cuasing intense itching

Question 9

How do we test for allergies?

Answer 9

Intradermal skin testing or serology

Question 10

How do we treat allergic skin disease?

Answer 10

• Flea control
• Hypoallergenic diet trial
• Topical shampoos
• Desensisitisation
• Medication

Question 11

Give examples of Allergic Respiratory Diseases in different species?

Answer 11

• Asthma or Hayfever in humans
• Feline asthma
• Allergic bronchitis in dogs
• Inflammatory airway disease in horses

Question 12

What causes bronchospasm in asthma?

Answer 12

Mast cell activation as a result of antigen - release of granuels causing smooth muscle contraction and mucous secretion with wheezing

Question 13

What is Inflammatory Airway Disease?

Answer 13

Allergic responses to mould spores in bad quality hay in horses causing coughing, wheezing, exercise intolerance

Question 14

How are bronchodilators used to treat allergic respiratory disease?

Answer 14

Administration of steroids/medicine (bronchodilators) via inhalation

Question 15

Give examples if Immune-mediated GIT diseases

Answer 15

• Gluten sensitive enteropathy
• Inflammatory bowel disease

Question 16

What is Gluten-sensitive enteropathy?

Answer 16

Hypersensitivity to gluten in the diet seen in dogs causing chronic diarrhoea and weight loss

Question 17

What is inflammatory bowel disease?

Answer 17

Inappropriate immune reactivity to dietary or enteric microbial antigens

Question 18

What are the underlying causes of inflammatory bowel disease?

Answer 18

Multiple causes:
- Increased intestinal permeability
- Inapproptiate IgE response to harmless antigen
- IgA deficiency
- Poor T regulatory cell responses
- Defective innate immune resposnes to bacteria