Feline asthma is a common progressive lower airway inflammatory disease thought to be due to an allergic response. Feline asthma is similar to human asthma in that hallmark features consist of airway inflammation, airway hyper-responsiveness, airflow limitation, and irreversible airway remodeling. Common symptoms include expiratory wheezing, coughing, and fast or difficultly breathing. Although many asthmatic cats’ symptoms are chronic, these symptoms are usually progressive, with or without treatment, and some cats may develop or present with life-threatening acute asthmatic attacks. Treatment usually involves glucocorticoids and bronchodilators. Many asthmatic cats respond well to glucocorticoids and bronchodilators; however, some cats are refractory to treatment. In addition, glucocorticoids are not necessarily innocuous and could be contraindicated with certain diseases such as diabetes mellitus and heart disease. These therapies do not reverse the abnormal immune response and they do not always prevent airway remodeling but may only slow disease progression.
Complicating the picture even more, there still is a lack of consensus on what defines asthma and how to distinguish it from other lower airway disorders such as chronic bronchitis, infectious or parasitic diseases, and heartworm associated respiratory disease. In this article, Drs. Trzil and Reinero from the College of Veterinary Medicine at University of Missouri, methodically present a review of current and new diagnostics and treatments for feline asthma.
Key points discussed in this review article are as follows: 1) definitive diagnosis of feline asthma is challenging due to overlapping clinicopathologic features with other lower airway disorders. Diagnosis is based on a combination of appropriate clinical signs, physical examination, routine blood testing (e.g., possible eosinophilia), and results of diagnostics tests. At this time, commonly used diagnostic tests may include thoracic radiographs, bronchoscopic examination, bronchoalveolar lavage cytology, and testing to rule out certain infectious and parasitic diseases (i.e., Mycoplasma spp culture or PCR, heartworm antibody/antigen, fecal floatation and Baerman examination for Toxocara cati and Aelurostrongylus abstrusus, respectively). Other diagnostic tests that may prove beneficial in the future include thoracic computed tomography and pulmonary function testing (e.g., barometric whole body plethysmography), 2) Traditional therapy using glucocorticoids and bronchodilators might be inadequate or contraindicated in some cats; therefore, novel treatments investigated in experimental models of feline asthma could be beneficial in refractory cases or used as adjuncts for glucocorticoids-sparing effects. Novel treatments showing promise or requiring further investigation include allergen-specific immunotherapy, omega-3 fatty acid supplement, inhaled lidocaine, tyrosine kinase inhibitors and stem cell therapy, and 3) Some therapies that were once thought to be beneficial, but were found to be ineffective include leukotriene antagonist, low dose serotonin inhibitors, second-generation antihistamines, immunomodulator salivary tripeptide (feG-COOH), doxycycline antibiotic, and N-acetylcysteine mucolytic/antioxidant. [GO]