Feline Large versus Small Airway Disease: Asthma, Bronchitis and Bronchiolar Disorders

摘要

Chronic airway disorders are among the most common types of respiratory diseases for which cats require veterinary attention. Historically, these airway disorders have centered on pathology of the large airways and include allergic asthma, chronic bronchitis and parasitic bronchitis. Diagnosis relies on a combination of historical and physical examination findings, typical thoracic radiographic features, ancillary testing to rule out other types of respiratory disease, and ultimately collection of airway lavage cytology. Recently, a new type of airway disorder has been described in cats that centers on pathology of the small airways. These small airways or "bronchioles" are defined as airways less than 2 mm in diameter that lack cartilage in their walls and are inclusive of terminal, respiratory and membranous bronchioles. As historical and physical examination findings and radiographic signs are not pathognomonic for small airway diseases, analysis of tissue is the criterion standard for diagnosis, and there is generally minimal cross-talk between clinicians and pathologists, the bronchiolar disorders have been overlooked as discrete respiratory syndromes in the cat. However, bronchiolar disorders may have substantial overlap in clinical signs and thoracic radiographic findings as the large airway disorders underscoring the importance of having these disorders on the differential list. The learning objectives of this lecture include: (1) to be able to discriminate feline asthma, chronic bronchitis and parasitic bronchitis (2) to be able to list and describe the classification scheme for bronchiolar diseases in the cat (three major categories) and (3) to be able to develop diagnostic plans to help discriminate these disorders.