Perspectives in veterinary medicine: Description and classification of bronchiolar disorders in cats

Reinero, Carol R.; Masseau, Isabelle; Grobman, Megan; Vientos-Plotts, Aida; Williams, Kurt

Disorders and exposures in humans leading to CBO include prior infection, inhalational injury (flavoring chemicals in microwave popcorn, e-cigarettes, coffee, and others [31] [32] [33] [34] , ingested drugs or toxins, autoimmune disease, and connective tissue disorders. 25 Humans present with clinical signs of an obstructive lung disorder with an insidious onset of progressive dyspnea and cough. 25 Thoracic radiography may be normal or show hyperinflation from air trapping; airway wall thickening also may be appreciated. 25, 35 High-resolution CT predominantly identifies mosaic attenuation, bronchiolectasis or bronchiectasis, and air trapping accentuated on expiratory views. 10, 27 Most cases are progressive, poorly responsive to corticosteroids and result in respiratory failure and death. 36 One cat in a case series had suppurative bronchopneumonia, bronchiolitis obliterans, and pulmonary fibrosis; it is unclear if this cat had a primary bronchiolar disorder or an ILD with secondary bronchiolar involvement. 18 Another cat in a case series had "fibrosing bronchiolitis" and "pneumonia" as histologic descriptors but not as the clinical syndrome or final diagnosis. 37 Recently, a reversible form of acute fibrosing bronchiolitis has been Excluded from the list of primary human bronchiolar disorders at this time are diffuse panbronchiolitis (described as predominantly occurring in humans of Asian descent with a genetic predisposition), respiratory bronchiolitis (a smoking-related airway disorder), and follicular bronchiolitis 59 (a lymphoproliferative pulmonary disease). b In the human classification scheme, "acute bronchiolitis" is used. This is a common disorder almost always secondary to infection in the pediatric population. We have revised the feline classification scheme to include acute and chronic infectious diseases affecting the small airways. c Excluded from the list of human bronchiolar disorders as a component of ILDs at this time are hypersensitivity pneumonitis (not yet recognized in cats), and respiratory bronchiolitis-associated ILD/desquamative interstitial pneumonia (smoking-related disorders).