Flashcards in Hopping with fleas! Deck (14):
Flea allergy dermatitis
Hair loss and skin lesions. Dermatitis is inflammation of the skin. Papules with crusts on his skin in the dorsal lumbar area.
Mast cells upon activation release 4 types of biological mediators
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
Affect voltage dependent sodium channels in nerve cell membranes causing repetitive discharges as a result of membrane depolarization.
Type IV hypersensitivy Reaction
Delayed hypersensitivity reaction. Because it is cell mediated.
What is IgE synthesis dependent on? Role of cytokines?
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.
Discuss why cross linking of IgE Fc receptors on mast cells is important in distinguishing a response between atopic and non atopic animals.
Some animals can have a higher affinity to the IgE receptor. Are they atopic?
Predisposition for IgE mediated hypersensitivity responses.
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.
Which class of drug is likely to be of most benefit when treating skin irritation associated with flea allergic dermatitis?
What is the mechanism of action of NSAIDs?
Cyclo-oxygenase enzyme inhibitor
What is the mechanism of action of antihistamines?
Histamine receptor antagonist
What is the mechanism of action of corticosteroids?
Alter transcription of DNA