Feline lower airway disease: asthma and beyond

Lower airway disease, and specifically bronchial disease, is common in cats, and a cause of significant morbidity and even mortality. The predominant presenting sign is a chronic cough, which may be mistaken by owners for ‘furballs’, as the cat may retch during a coughing episode. Inflammatory bronchial disease is the most common lower airway disease in cats (Foster et al, 2004a), and is frequently termed ‘feline asthma’. However, feline asthma likely represents just one end of a spectrum of non-infectious, inflammatory, lower airway diseases seen in cats, with chronic bronchitis also associated with significant respiratory morbidity in this species. Veterinary nurses have an important role to play in the diagnosis of feline lower airway disease, and the emergency and chronic management of affected cats.

The term ‘asthma’ is used in human medicine to describe a condition caused by spontaneous bronchoconstriction and airway remodelling, often presenting with dyspnoea, and responding to treatment with bronchodilators (Reinero et al, 2009a). In cats, although a subset of patients will present in this way, the majority have a chronic cough. To complicate the classification of non-infectious, inflammatory bronchial disease in cats, many have predominantly neutrophilic airway inflammation, or a mixed cell cytology on bronchoalveolar lavage (BAL). This is in contrast to the predominantly eosinophilic inflammation classically seen in feline asthma. Standardisation of terminology is not currently available and many consider non-infectious inflammatory bronchial disease in cats to be a spectrum (Rozanski, 2016), as illustrated in Figure 1, and in a clinical setting, without BAL, defining the underlying condition may not be possible.