Therapeutics
Treatment options are summarized below and have been reviewed in more detail elsewhere (Hawkins and Papich 2014; Padrid 2014; Trzil and Reinero 2014; Reinero 2015).
Supportive Measures
• Weight loss
• Environmental temperature control
• Avoiding airway irritants
• Regular anthelmintic treatment, heartworm prophylactics in endemic areas, ecto- and endoparasite control.
Medical Therapy
• Oxygen
• Anxiolytics
• Bronchodilators - administrated via inhalation (metered dose inhaler with face mask or nebulization), parenteral or oral formulations.
• Corticosteroids remain the mainstay of medication used to modulate airway inflammation and are considered the primary treatment after emergency stabilization.
• Novel, alternative, or ancillary therapies, which may be beneficial, but with good clinical veterinary evidence lacking:
î Inhaled lidocaine (Nafe et al. 2013) î Tyrosine kinase inhibitors (Bellamy et al. 2009; Lee-Fowler et al. 2012) î Omega-3 polyunsaturated fatty acids î Stem cell therapy (Trzil et al. 2014; Trzil et al. 2015)
î Cyclosporine has been used with success where corticosteroids were not tolerated (Nafe and Leach 2014).
• Allergen specific immunotherapy
• Antibiotics - have no role in either acute or chronic cases of feline inflammatory airway disease, which is primarily a non- infectious disorder. Secondary bacterial infections do on occasion complicate cases, requiring appropriate anti-microbial therapy.
• Heartworm diagnostics and treatment in endemic areas
• Ineffective therapies (Schooley et al. 2007; Trzil and Reinero 2014; Grobman et al. 2015a, 2015b):
î Leukotriene inhibitors
î Cyproheptadine
î Antihistamines (cetirizine)
î Inhaled N-acetylcysteine
î Neurokinin-1 receptor antagonist - maropitant
Approach to the Acute Patient in Crisis
Acute therapy usually refers to treatment of patients presenting with acute respiratory distress or status asthmaticus.
Emergency therapy includes supplying oxygen and administrating anxiolytics and corticosteroids. Bronchodilators are critical to successful emergency management and asthmatic crises are best treated by using injectable formulations. Antitussives in the acute setting are generally not required as coughing is a marker of the underlying asthmatic disease. Treatments must be administered without excessive physical restraint or exacerbating anxiety, both of which increase oxygen demand and breathing effort in an often extremely compromised and hypoxic patient.Approach to Chronic Management
Chronic treatment goals are to control the airway inflammation and decrease airway remodeling. Corticosteroids are currently still considered the primary treatment for management of feline asthma, despite their side effects. Oral, injectable, and inhaled formulations have all been used successfully. Inhaled formulations for chronic management carry the least risk of systemic side effects and remain first choice. Not all cats can be controlled with inhaled formulations alone; others will not tolerate this administration route. Bronchodilators are rarely required as an ongoing therapy, but held in reserve for acute episodes of bronchoconstriction. They play no role in managing airway inflammation and should not be used as monotherapy.
Patients have traditionally been started on a high dose of glucocorticoids with treatment being tapered to the lowest effective dose based on resolution of clinical signs (wheezing, increased inspiratory rate and effort, coughing, etc.) together with improvement of radiographic changes. This practice is, however, less than ideal. In cats with controlled clinical signs, up to 70% had persistent sub-clinical airway inflammation based on repeat BAL cytology (Cocayne et al. 2011). Additionally, asthma waxes and wanes in severity, making assessment of treatment responses difficult and thoracic radiographs may be normal in a good proportion of asthmatic cats. Best-practice recommendations may develop over time to monitoring treatment success objectively by means of repeat BAL cytology.