Changes

Mast cells secrete mediators which cause:

Mast cells secrete mediators:

* The release of inflammatary cytokines

* The release of inflammatary cytokines which can cause the dog to become itchy.

**Steroid mediators, e.g. prostaglandins and leukotriens

**Steroid mediators, e.g. prostaglandins and leukotriens

*Chemoattractants (attracts mainly neutrophils but also eosinophils, monocytes and basophils and plasma)

1. Chemoattractants (attracts mainly neutrophils but also eosinophils, monocytes and basophils and plasma)

2. Vasoactive and inflammatory peptides (e.g. histamine and serotonin) which causes acute contraction of smooth muscle fibres  

*Vasoactive and inflammatory peptides (e.g. histamine and serotonin) which causes acute contraction of smooth muscle fibres  

**If the allergen is inhaled (locally) it can lead to bronchoconstriction.

**Leading to bronchoconstriction and vasoconstriction (if the allergen is )

3. Mucus production - due to the release of mast cell proteases

**Violent constriction can lead to the expulsion of parasites

4. Vasodilation (leads to redness and heat).

*The release of mast cell proteases

5. Oedema (from leaky blood vessels).

* Vasodilation (leads to redness and heat)

* Oedema (from leaky blood vessels)