Hopping with fleas!

Question 1

Flea allergy dermatitis

Answer 1

Hair loss and skin lesions. Dermatitis is inflammation of the skin. Papules with crusts on his skin in the dorsal lumbar area.

Question 2

Mast cells upon activation release 4 types of biological mediators

Answer 2

1. Lipid mediators- leukotrienes, C4, D4, E4- cause smooth muscle contraction increase vascular permeability and stimulate mucus secretion
2. Biogenic (vasoactive) amines released from mast cell cytoplasmic granules- Histamine- causes increased vascular permeability and smooth muscle contraction
3. Granule enzymes released from mast cell cytoplasmic granules- Tryptase- remodel connective tissue matrix
4. Cytokines- IL-4, interleukin, stimulate and amplify T helper cells

Question 3

Pyrethrins

Answer 3

Affect voltage dependent sodium channels in nerve cell membranes causing repetitive discharges as a result of membrane depolarization.

Question 4

Type IV hypersensitivy Reaction

Answer 4

Delayed hypersensitivity reaction. Because it is cell mediated.

Question 5

What is IgE synthesis dependent on? Role of cytokines?

Answer 5

Dependent upon activation of TH2 CD4 helper T cells. Cytokines will stimulate and amplify TH2 cells and some will also promote eosinophil production and activation, promote inflammation, stimulate cytokine production by many cell types and activate endothelium. Because of IL-4 and IL-3 they are the ones that amplify helper T cells.

Question 6

Dipylidium caninum

Answer 6

Flea tapeworm

Question 7

Discuss why cross linking of IgE Fc receptors on mast cells is important in distinguishing a response between atopic and non atopic animals.

Answer 7

Some animals can have a higher affinity to the IgE receptor. Are they atopic?

Question 8

Atopy

Answer 8

Predisposition for IgE mediated hypersensitivity responses.

Question 9

Dipylidium caninum

Answer 9

Flea tapeworm. Cyclophyllid cestode that infects organisms afflicted with fleas. Adult worm is 18 inches long. Worms microscopic eggs are either passed in the definitive host’s faeces and then ingested by microscopic flea larvae. The larvae then pupate and transform into adult fleas still carrying the tapeworm, which is then ingested by dog or cat during grooming. The worm enters the digestive tract and anchors itself to the intestinal wall.

Question 10

Which class of drug is likely to be of most benefit when treating skin irritation associated with flea allergic dermatitis?

Answer 10

Corticosteroids

Question 11

What is the mechanism of action of NSAIDs?

Answer 11

Cyclo-oxygenase enzyme inhibitor

Question 12

What is the mechanism of action of antihistamines?

Answer 12

Histamine receptor antagonist

Question 13

What is the mechanism of action of corticosteroids?

Answer 13

Alter transcription of DNA

Question 14

What are the side effects of corticosteroid treatment?

Answer 14

Polyuria, polyphagia (eating a lot), polydipsia, diabetogenic, hepatomegaly