Feline Asthma Syndrome
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Also known as Feline Allergic Bronchitis
Description
Feline asthma is an allergic airway disease that bears many similarities with asthma in humans and with recurrent airway obstruction (RAO) in horses. Affected animals become allergic to allergens present in their immediate environment, including house dust mites and fungal spores and produce IgE antibodies against these molecules. When later exposed to the same allergens, asthmatic cats suffer a form of type I hypersensitivity response localised in the bronchi and bronchioles and resulting in constriction of the airways.
Cases of feline asthma may be divided into intrinsic and extrinsic disease.
Extrinsic asthma
Type I hypersensitivity in response to allergen challenge - mediated by IgE. Pathological changes include:
- Exudate into airways - mucus/ cells
- Thickened airway walls - oedema, glandular and smooth muscle hypertrophy, vascular congestion
- Altered fluidity of mucus (associated with goblet cell hyperplasia) -> less effective mucociliary apparatus
Intrinsic asthma
In a proportion of cats there is an increased propensity for the bronchial smooth muscle to contract (increased bronchial reactivity) -> airway constriction