The Pathologic Link between Lung and Gut: Diagnosis of Aerodigestive Disorders in Dogs
Aerodigestive diseases are defined as hybrid disorders representing a pathologic link between the respiratory and alimentary tracts. Aside from macroaspiration causing aspiration pneumonia, disorders associated with chronic microaspiration are poorly recognized but contribute to respiratory disease development, exacerbation and progression. Reflux, an important source of microaspirated contents, has been documented in up to 90% of humans with chronic cough, asthma, chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis. Importantly, as reflux may occur in the absence of clinical signs of heartburn or regurgitation, its underlying contribution to respiratory disease is masked.
Dogs with aerodigestive disorders presenting solely for respiratory clinical signs in absence of dysphagia, vomiting or regurgitation do not receive diagnostics targeting alimentary tract disease. This is of critical clinical importance as contributory but unrecognized alimentary tract disorders represent a novel target for therapy. Unrestrained, free-feeding videofluoroscopic swallow studies (VFSS) allow non-invasive assessment of functional defects in swallowing, pathologic reflux and aspiration. Pilot retrospective data from our laboratory suggests aerodigestive disorders are common in dogs with respiratory disease 25/31 (81%) of dogs with cough in the absence of dysphagia, vomiting and regurgitation having at least one VFSS abnormality. A prospective study in dogs with respiratory disease/no alimentary disease compared to healthy controls lacking both respiratory and alimentary disease using metrics derived from VFSS is needed to determine how common and which types of VFSS abnormalities impact respiratory disease. This study represents the first step towards therapeutic targeting of comorbid, silent alimentary tract disease in dogs with respiratory disease.
Forty-five dogs presenting for clinical signs of cough, audible respiratory noise (stertor, stridor or wheeze), or labored respiration in the absence of dysphagia, vomiting and regurgitation in the prior 2 months will be evaluated using a comprehensive series of respiratory diagnostics and a VFSS. Diagnostics will include functional upper airway exam using doxopram to assess laryngeal excursion, ventilator-assisted inspiratory and expiratory breathhold cervical and thoracic computed tomographic (CT) scans, tracheobronchoscopy, and bronchoalveolar lavage for cytologic examination and culture. Dogs will be excluded if they have primary nasal cavity or pleural cavity disease, cardiac failure (cardiogenic pulmonary edema), or are unstable for general anesthesia.
Provide relevant historical information requested by clinicians about clinical signs relating to the respiratory and alimentary tracts. Provide informed consent for respiratory diagnostics and VFSS.
Name: Carol Reinero
Help Future Generations of Dogs
Participate in canine health research by providing samples or by enrolling in a clinical trial. Samples are needed from healthy dogs and dogs affected by specific diseases.