You have asked…Are inhaled corticosteroids effective for managing chronic inflammatory airway disease?
The expert says…
Airway disease is classified as acute or chronic. Acute airway disease is represented by such conditions as infectious tracheobronchitis, while common chronic airway diseases include canine chronic bronchitis and feline lower airway disease (asthma). It is important to recognize that ongoing therapy is key in achieving successful outcomes in patients with chronic conditions. Conditions such as epilepsy or atopy are controlled, not cured, and chronic airway disease should follow the same treatment paradigm.
To identify the etiology of chronic airway disease, treatable causes of cough and airway inflammation must first be excluded, including Mycoplasma or Bordetella bronchiseptica infection, cardiac disease with left atrial enlargement and progressive compression of mainstem bronchi, laryngeal dysfunction, parasitic disease, presence of airway foreign bodies, or neoplastic disease.
INFLAMMATORY AIRWAY DISEASE
Glucocorticoids, such as prednisone, are the mainstay of therapy for inflammatory airway disease in small animals. However, oral corticosteroids have significant side effects in dogs, including polyuria/polydipsia, weight gain, behavioral changes, and hepatomegaly. Cats have shown increased tolerance to the side effects of glucocorticoids, but oral glucocorticoid administration has been associated with a greater incidence of diabetes mellitus and repositol products have been associated with congestive heart failure in cats.1
Inhaled corticosteroid (IC) drugs are the first-line treatment for humans with asthma and other inflammatory airway diseases and have been proposed as treatment for moderate to severe steroid-responsive lower airway disease in both dogs and cats.
Inhaled β2-agonists (eg, albuterol) are also widely used for bronchodilation in humans with asthma, although recent studies have demonstrated increased mortality and decreased therapeutic efficacy associated with frequent use.2 Inhaled β2-agonists are warranted for management of asthma and associated bronchoconstriction in small animals, which occurs in some cats with airway disease but typically not in dogs.
INHALED GLUCOCORTICOIDS
The primary advantage of ICs is that they avoid or minimize the systemic side effects associated with oral glucocorticoids while targeting therapy to the lungs. In a 2008 study, Cohn and colleagues4 showed that IC drugs suppressed the hypothalamic–pituitary axis of dogs but had limited effects on the immune system. IC drugs do increase the risk for diabetes in humans, but the diabetogenic effects of these medications in cats have not been evaluated to date.
Because voluntary cooperation is lacking in pets, administration of IC drugs requires use of a face mask and spacer (Figure 1). Several models are available, but the AeroKat and AeroDawg chambers (trudellmed.com/animal-health) seem to be widely used (Figure 2).
Most pets require a period of acclimation to accept the mask and treatment. In addition, the owner could be exposed to the aerosolized product, although in clinically insignificant amounts.