Feline chronic inflammatory airway disease with a focus on feline asthma

Feline chronic inflammatory airway disease with a focus on feline asthma The term feline chronic inflammatory airway disease is used to describe a spectrum of inflammatory diseases of the bronchi of unknown aetiology, with feline asthma (FA) und chronic bronchitis (CB) being the most important. FA has numerous parallels to allergic asthma in humans, and clinically manifests as chronic cough, wheezing and/or paroxysmal respiratory distress, in addition to other signs. Characteristic findings include bronchial wall thickening due to inflammatory infiltrates and oedema, reversible bronchoconstriction, and increased sensitivity to non-specific stimuli (non-specific airway hyper-responsiveness). As in human medicine, the proposed mechanism of the allergic process is an imbalance between Th1 und Th2 immune cell responses with predominance of a Th2 cytokine pattern. Clinical signs are indicative, but not pathognomonic for the disease, and no simple blood tests to support diagnosis are currently available. Diagnosis is established based on compatible clinical signs, radiographic changes, the presence of eosinophilic lower airway inflammation (broncho-alveolar lavage fluid analysis) and the exclusion of other known causes of feline bronchial inflammation (e.g. parasitic disease). Non-invasive pulmonary function tests (barometric whole body plethysmography) allow for the detection and quantification of asthma-associated expiratory airflow limitation in the conscious patient. In the emergency setting, rapid differentiation between bronchoconstriction and other causes of acute respiratory distress, as well as the evaluation of the effectiveness of emergency treatment is possible with these tests. Since the avoidance of allergen exposure is seldom practical, long-term treatment is accomplished by the administration of glucocorticoids and certain bronchodilatators. Inhaled steroids, using spacers, have been used extensively in the treatment of FA and CB over the last few years. In the future, allergen-specific immunotherapy (hypo-sensitization) may represent a new and more specific form of treatment. Whereas allergen-specific immunotherapy in experimental FA induced by known allergens reduced airway inflammation, little information exists regarding its use in clinical patients, due to the current problems associated with the definitive identification of disease-inciting allergens.